Crime Watch Daily Exclusive: Mistress speaks out about details in murder case of ex-lover's wife

No one wants to know what happened to Desiree Sunford more than her mother Connie Kast.

"My heart will never be whole again," Connie tells Crime Watch Daily. "My health has been greatly declining. Now I am stuck with oxygen, heart failure, to go along with my mental anguish."

Thank you for the courage to tell Desiree's story.

"That's the only thing I can do for her now is to make sure that everyone hears her story," said Connie.

The story of Desiree Sunford is a classic tale of "Never Judge a Book by Its Cover."

By day Desiree was a much-adored but nerdy art teacher.

"The kids loved her. Always happy, always moving," said Desiree's godmother Glenda Jenkins.

But by night, Desiree was a born-to-be-wild Harley-riding motorcycle mama.

"She learned how to ride, bought herself a Harley-Davidson and hit the road," said Connie Kast.

And always by her Desiree's side was her husband Scott, an ex-Army mechanic who served two tours in Iraq.

"They were high school sweethearts," said Connie.

For nearly two decades the young couple was practically inseparable.

"I never really warmed up to him totally," said Connie. "Occasionally he would say or do something that got my dander up."

And there was one thing that really brought out the mama bear in Connie.

"She was concerned I think about his fidelity, but there was never anything that we could prove or substantiate that he was being unfaithful," said Connie.

Despite Desiree's suspicions, she stood by her man. The couple even bought their first home together just outside the city limits in Yakima, Washington.

"She was excited about the new house, and life was just good," said Connie.

But just six months after moving in, there's trouble in paradise.

"There was a burglary at Scott and Desiree's residence," said Yakima County Sheriff's Detective Chad Michael.

Detective Michael says the burglar smashed through a pane of glass in the back door and ransacks the house.

"Firearm, computers," said Det. Michael.

Scott Sunford temporarily patches the broken glass and steps up security.

"They had a security system installed," said Det. Michael.

To give them a chance to get used to the new system, the security company only sends alerts to Scott and Desiree. The cops are not notified.

"So if the alarm is tripped it goes to the homeowner's cellphone connection," said Det. Michael.

A few days after the alarm is installed, Scott heads out of town for his aunt's funeral. It's about an hour outside of Yakima.

At 3:24 that morning, Scott gets an unexpected wake-up call.

"Scott did get an alarm notification that someone was entering his house," said Det. Michael.

Just three minutes later, at 3:27 a.m., he gets a second alarm. Then one minute later, at 3:28, a third notification lights up his phone.

Scott assumes Desiree accidentally tripped the alarm letting their dog out, and he goes back to sleep. He does not call the sheriff's office.

Later that afternoon, Scott heads home. On the way back to Yakima, he finally checks in on Desiree.

After a few unanswered calls, Scott starts to worry those tripped alarms in the middle of the night were no accident, and he calls 911.

"Sheriff's office."

"Hi ma'am, this is Scott Sunford. Today at 3:24, 3:27 and 3:28 I had three sensors tripped."

"OK, did somebody break into the residence?"

"I don't know, I've been out of town and I haven't been able to get ahold of the wife."

"He was concerned about her and he wanted the sheriff's office to send someone out to check his house. A wellness check," said Det. Michael. "He has not arrived at the house yet."

"As soon as I have somebody available I will send them out to your address, OK?"

"OK, thank you."

Twenty minutes later Scott Sunford pulls in his driveway. The cops aren't there yet, but as he drives in, panic strikes. Scott makes a second, more desperate 911 call.

"I just got home and the board that I have over my back door has been broken, so somebody has forced their way in again, and I still haven't heard back from my wife. I need an officer here now."

"All right, we'll get someone out there."

"I'm not gonna go in and touch anything, but I'm here in the car and I got a spotlight on the door."

Wait a minute -- his wife could be in danger, and this ex-military man tells cops he's not going in?

It just strikes me as bizarre that he would get to the house and then wait for a deputy to accompany him inside.

"Certainly, yeah," said Det. Michael. "Scott's a big guy, I've seen him. He's about 6' 5", maybe 230-240, military-trained. He's got his sidearm on him. And he waited outside of his house for law enforcement to arrive to search the house."

Within minutes a Yakima County deputy arrives wearing a body camera. Scott, who's packing a pistol, is still waiting in the driveway.

"If you thought something was wrong, why didn't you go in?" said Connie Kast, Desiree's mother.

The deputy wearing the body-cam spots that broken door, then cautiously enters the home in case the burglar has come back and is still lurking inside. With gun drawn, he peers around each corner until he finally finds a light switch, and when he flips it on:

"My whole world just came to a sudden stop, and life as I knew it would never be the same again," said Connie.

Desiree Sunford was found partially naked and brutally murdered on April 7, 2013.

"My doorbell rang and I opened the door to two Grant County sheriff deputies and they informed me that my daughter's body had been found, that she had been shot to death, murdered in her home," said Desiree's mother Connie Kast.

It appears the 30-year-old art teacher tried to crawl away but couldn't escape a fatal 9mm bullet to her head.

Did Desiree have any enemies you know of?

"No, no, not at all," said Desiree's godmother Glenda Jenkins.

"She was a friend to everyone, so it boggled my mind to think of that, you know, who could have possibly had that much aggression against her to kill her?" said Connie.

Initially Desiree's husband Scott Sunford told investigators he suspected a burglar who'd hit their house just a week before, had returned, and this time had taken Desiree's life when she caught him in the act.

Did you buy that story or theory?

"Not really," said Connie.

Neither did the Yakima County Sheriff's Department, so detectives haul Scott Sunford in for questioning. But while Scott waits in the interrogation room, deputies notice something odd.

"Don't think about your wife, don't think about her," Scott whispers to himself.

Instead of mourning Desiree's horrific death, Scott appears to be psyching himself up for the questions to come.

"Calm down, here comes a cop. Come on, knock it off."

"It doesn't seem like his emotions were on par with the situation," said Yakima County Sheriff's Detective Chad Michael.

Investigators begin with the burning question on everyone's mind.

"It sounds like by the time you actually made it to the house, you were pretty frantic. You felt like something had gone wrong."

"My stomach was churning, I was shaken, I had convinced myself by that point that something had to be wrong."

"So why not go in the house and check things out and make sure she's OK?"

"'Cause I was afraid."

Afraid? The tough, pistol-packing military guy was scared?

"Even if you're afraid that the bad guy is still in there, this is your wife. You're going to leave her in there to fend for herself with the bad guy?" said Connie.

Desiree's mother Connie Kast and Yakima County detectives begin to wonder if Scott didn't enter the house because he already knew what he was going to find.

"Well, it's not that I was afraid of anybody being in there."

"You just didn't want to see what may have happened to her?"

"Yeah."

"He was considered a suspect in this case," said Det. Michael.

But Scott Sunford maintains he's completely innocent, and offers up an ironclad alibi: He was an hour outside of Yakima for a family funeral.

"Then you stayed at your dad's in Kennewick?"

"Uh no, I actually stayed with a friend."

A female friend.

"Was it just a platonic friendship, or was it sexual relationship?"

"No, and honestly we didn't do anything. I was out on the couch."

Here's where Scott's alibi gets complicated: the woman is Scott's alibi, and they've got a secret.

She's sitting down with Crime Watch Daily for her first interview ever. We're protecting her identity per her request.

"He came and spent the night at my place," the woman tells Crime Watch Daily.

Scott said he slept on the couch. Is that true?

"No. No, it's not," the woman says. "If he was in my house, he was in my bed."

You wanted to conceal your identity and we're not using your name, we're respecting your wishes. We helped disguise and alter your identity.

"Right," she says.

She says she is finally ready to come clean about what happened in the days and months leading up to Desiree Sunford's horrific murder.

When you met Scott, did you know he was married to Desiree?

"I knew that he was married but I had been told that he was separated."

At what point did you and Scott start to get intimate?

"Actually it was the day that I found out that he was still actively married."

And you're the mistress?

"I didn't see myself being a mistress long-term. I also wasn't entirely sure I wanted to date him, but sex was cool. So I went with that."

The mistress tells Crime Watch Daily that shortly after the affair started, Scott concocted an elaborate plan to introduce her to Desiree, telling his wife she was dating his buddy.

Why did you and Scott want to arrange this meeting?

"We didn't want her to be suspicious."

Did you guys hit it off?

"Oh yeah, yeah, from the very beginning actually. We became very, very close. I helped her plan Scott's 30th birthday the following month."

While you're still sleeping with Scott?

"Yes."

And does she have any idea?

"Not at the time, no."

The mistress says she and Desiree got a little too close for comfort.

"I was living with them part-time, we all slept in the same bed."

How big is this bed?

"It's a California King. No, we all shared the same bed, and at the time it was Desi in the middle, and eventually it moved to Scott being in the middle."

Is it possible Scott wanted to kick Desiree out of the bed for good, and the mistress was motive for murder?

Scott's wife is dead. Scott's not with her when she is gunned down. You find out now that he has an affair, so if you're looking at motivation ....

"Sure, yeah, there's red flags that pop up," said Det. Michael.

But when the detective grills Scott about the affair, he tells him he's got it all wrong.

"You know I shouldn't go there because it's kind of rude, but, well, Des didn't want me to say anything to anybody, but at one point her and [----] had a little thing going for a while there."

"So it was Desiree and [----] who had a sexual relationship going."

"We all did. Honestly, we all did."

You are sleeping with Desiree's husband unbeknownst to her at the time.

"Yes."

But then you start sleeping with Desiree.

"And at that point it was, 'Well, let's just do it all together.' It evolved into a polyamorous relationship."

So to be clear, all of you are having a consensual open relationship?

"Yes."

All of you are having sex with each other.

"Yes."

And how long did this threesome last?

"Up until right before she was murdered, actually."

The mistress tells me she and Scott never wanted to get rid of Desiree. They both loved her.

But after the murder, you're still seeing Scott.

"Yeah. Yeah."

"I was under the thinking of Scott and his mistress had something to do with it," said Connie Klast.

Quite the coincidence.

"Yeah. Perfect alibi," said Connie. "They were together, so he said 'She didn't do it because she was with me,' she said 'He didn't do it because he was with me.'"

The mistress is now making the claim that her, Scott and Desiree were in a polyamorous relationship.

"I can safely say that my daughter would never have participated in such an act," said Connie.

No threesomes going on.

"Absolutely not," said Connie.

Detectives also find the alibi shaky, but there's no proof Scott or his mistress had anything to do with Desiree's murder. In fact investigators actually discover mystery DNA and a bloody shoeprint at the crime scene that doesn't belong to either one of them.

"It's one of those cases where you just start scratching your head trying to figure out what is going on here," said Det. Michael.

And after months of hitting dead ends, the case goes cold.

"There wasn't anybody else to look at," said Connie.

Then, a year and a half after Desiree Sunford was gunned down inside her home, a tip is called in to Crime Stoppers saying they know who murdered the young teacher.

Who was this tipster?

"The tipster in the situation was the mistress," said Det. Michael. "Scott's mistress."

"I knew that he had been with me all night. I knew that there was no way that he could have done it."

The mistress tells me in this Crime Watch Daily exclusive that there was no reason for Scott to kill Desiree, claiming she was well aware of the affair.

In fact, she says Desiree was a willing part of a happy love triangle.

You're having sex with Desiree.

"I'm having sex with Scott."

Desiree was having sex with her husband. You are having sex with Scott.

"Yes."

Everyone is on the same page.

"Exactly."

But was there a motive about to be delivered?

You find out you are pregnant with Scott's kid?

"Yeah."

The happy threesome was about to become an incredibly awkward family of four.

He didn't want Desiree to find out?

"He never said that but probably. Very probably."

Still, cops don't have proof. And remember: there is mystery DNA and a bloody shoeprint found at the crime scene that doesn't belong to Scott Sunford.

A year and a half goes by, then a call comes in to the Crime Stoppers tip line. It's the mistress telling cops that someone has confessed to murder.

"I put it into the Crime Watchers tip line. They were like, 'This is information that we never released to the public and the detectives would like to talk to you.'"

"He made sure that everything was wiped down completely clean, no fingerprints on anything, none of the bullets, reloaded the clip, turned his phone off before he left the house."

We've blurred the mistress's face to keep her true identity hidden in video of her being questioned by investigators. But what she tells police is crystal-clear.

"He asked me if I wanted him to take care of this new woman like he did Des."

The mistress isn't talking about her lover, Desiree's husband Scott. She says the killer is a man named Marty Grismer -- who just happens to be the mistress's best friend.

Tell me about Marty Grismer.

"What do you want to know?"

How did you meet him?

"At work actually. At one point I went out on a date with Marty and it was a really bad idea."

Did you and Marty ever have sex?

"No. No. He tried really hard, and it wasn't happening."

Would you say Marty was infatuated with you?

"No, Marty was obsessed with me. He would always tell me how perfect I was, and how much he loved me, and adored me, and cherished me and would do anything for me."

Anything, including murder.

"He said 'Well I am the one who killed Desiree, didn't you know that?' No. Actually, I didn't."

What did Marty tell you?

"He reenacted what he had done and how he had made it look like a break-in. He told me eventually everything."

"Apparently he decided that if the baby was Scott's, then Desiree would cause issues. Oh my God."

The mistress told detectives she and Marty actually talked about the best way to kill people, but she thought it was all a joke.

You and Marty, they say, have this hobby debating how best to kill someone, dispose the body, and get away with murder.

"How to build the perfect crime."

You know normal people don't talk about planning death, right?

"I do know that."

A normal hobby is fishing, hot yoga, origami, not planning out murder.

"That's true, that's very true. But those were never my hobbies."

Why did Marty tell you he murdered Desiree?

"All he would tell me was, 'To make you happy,' and I said 'Well why did you think that that would make me happy?' And he says 'Because now you're gonna have this baby, I wanted you and Scott to be able to start a fresh life.'"

Investigators ask the mistress to wear a wire. They want to get Grismer's confession tape.

"You said that there was no evidence? So I'm just wondering for sure, for sure if there's nothing left."

"I don't know what you're talking about. I don't have anything. Never done anything."

But it backfires. Grismer denies everything. Then the mistress tells cops she's got another ace up her sleeve, claiming she knows where Grismer stashed the things he took from the crime scene, and better yet, where he hid his gun.

"He had a gun barrel in his drawer at work," said Det. Chad Michael. "That gun barrel was found, after forensics examination, to have been used in the homicide."

Detectives haul Marty Grismer in for questioning.

"It's just a simple yes or no question: Did you kill her?"

"No I did not."

"She's saying that, you know, you did this, you did that, you drove your own car to Yakima and it was your gun, and guess what? The barrel of that gun is in your possession."

"I never killed anyone."

Well, he denies it.

"Yeah," said Det. Michael.

Grismer adamantly denies having anything to do with Desiree Sunford's murder, claiming he's been framed by the woman he worshipped and adored.

"She's trying to engineer, set me up here, or do something by saying to you that I am the one that killed someone -- that, it makes me sick."

Suddenly Marty Grismer makes his own shocking allegation, telling detectives it's the mistress who had Desiree murdered.

"What I know is that [----] had this arranged, that's all I know."

He's saying she's the one who is involved.

"Trying to punt the responsibility onto her," said Det. Michael.

Grismer tells detectives he loaned the mistress his gun months earlier, and now he believes she planted the evidence to set him up.

"It's my word against hers on all of that on there, and what's going through my head is that 'I'm screwed for life, and I've done nothing.'"

Grismer's right. But it's not only the mistress's sworn statement that buries him. Remember that bloody shoeprint? It turns out it's the same size and brand of shoe Grismer wears.

Prosecutors charge Marty Grismer with murder in the first degree.

"Detectives were very confident that they had the right guy," said Det. Michael.

But Desiree's mother Connie Kast isn't so confident Grismer acted alone.

"I can believe that he did the deed by himself, but how did he know that Desiree was gonna be alone that night?" said Connie. "My theory was that Scott and his mistress gave Marty the information that she was going to be alone."

And Connie says that's not the only thing that makes her believe there was a conspiracy to have her daughter murdered.

Remember the baby the mistress was carrying when Desiree was killed? Turns out Scott wasn't the father.

Scott's mistress was pregnant with some other guy's child.

"But said that it was Scott's," said Connie.

Connie believes the mistress knowingly lied about Scott being the father and about her relationship with Desiree.

So we started to dig deeper into the mistress's story and uncovered explosive text messages that may blow the case wide open.

Desiree writes to you, quote, "Your guys' comfort level with each other is much higher than I'm OK with" -- this is you writing to her: "I'm sure I could have sex with him, I just don't think about it because he's married." So cut the crap with me now. You were not in an open relationship with Scott and Desiree.

If you weren't sleeping with Desiree's husband, would she still be alive today?

"I don't know."

The mistress says she didn't kill Desiree and neither did Desiree's husband Scott. She points the finger at her best friend Marty Grismer as the killer, and claims he actually confessed to her.

Why did Marty tell you he murdered Desiree?

"He wanted me to be happy. That was always his end goal, was my happiness."

Here's the problem: We've uncovered some glaring inconsistencies in her story.

I'll start from the beginning. Were you in an open relationship with Desiree and Scott?

"Yes."

Desiree was approving your having sex with Scott.

"Yes."

And you were having sex with Desiree?

"Mmhm."

That's your final answer.

"Yes."

You're lying to us right now. You're a liar.

"I'm not lying."

If she's not lying, how does she explain text messages we found? Desiree sure doesn't sound like she's condoning any hanky panky, or any kinky threesome.

Desiree writes "I'm just getting frustrated. You two chat and show pics, and I tend to get left out. One of you leaves, the other hops out too. It's adding up, but over time it's starting to bug me." You write: "I try to stay out of the way as much as possible. I understand if you don't want me here." Desiree said there's something wrong here. See, Desiree is on to something. She's saying "There's something not right about this relationship you have with my husband." So you can cut the act that she was approving of anything you were doing. In fact, she's suspicious here that you're having an affair.

"I don't remember that conversation."

Oh you don't remember? Well, let me remind you of another one. This is you writing to her: "If you ever die and he needs a wife, I'm half convinced that would be me." Just coincidence a year later Desiree does end up dead. You were not in an open relationship with Scott and Desiree.

"We were."

No. I'm just reading text messages to you that suggest blatantly the exact opposite.

The mistress also claims Marty Grismer was just an annoying friend who had a sexual obsession with her -- an almost fatal attraction.

While we're on the subject of your honesty, you said Marty was obsessed with you, but you never had any type of sexual relationship with Marty.

"Right."

What about the nude photo exchanges between you two?

"Yeah, there were definitely nude photo exchanges."

Between you two?

"Yes."

Did you wonder why Marty may have been obsessed if you were sending him nude photos?

"But that's not having sex."

That's a sexual relationship if you're sending nude photos. "Here's my private parts, but it's not sexual."

"Yeah, but I send them to a lot of people."

"Here's a nude shot."

"Most of the photos that Marty got, Scott also got, so did Scott's dad."

You were close with Scott Senior as well?

"Yeah."

Did you and Scott Senior fool around?

"Yeah, yeah, we fooled around, but we never had sex."

Despite all of her inconsistencies, and the suspicious behavior of Desiree's husband Scott, cops say the evidence still points to Marty Grismer as the lone killer, and prosecutors charge him with first-degree murder.

But in an odd courtroom twist, Grismer takes what's called an Alford Plea.

"Which essentially says that the case, the state has a good case and it could find him guilty if he fights it," said Det. Chad Michael.

But Grismer maintains his innocence with this plea. Ever run through your mind that maybe the mistress and Scott set him up and used Marty as a patsy?

"There will always be questions, I suppose," said Det. Michael.

As far as this investigation goes, is the case closed?

"The case is closed," said Det. Michael. "Yeah, we're done. We've moved on."

What was running through your mind when he took that deal?

"My heart hit the floor," the anonymous woman says. "I was extremely angry. I cried a lot. I didn't feel like justice had been done. There was a lot of anger. I still get mad about it."

You can stop the tears. You know I don't buy a word you're saying.

"My story has been the same from the beginning."

Marty Grismer was sentenced to 15 years behind bars. But there is an interesting catch. As part of the Alford Plea deal, Grismer does have one year to change his mind and fight the murder charge in court.

"Justice was not served by that sentence," said Connie Kast.

Does it bother you that you have one guy who is serving 15 years in prison for gunning down your daughter, but other people may have gotten away scot-free?

"Oh, it drives me bonkers. Every time I think of Scott running around happy-go-lucky, it just infuriates me," said Connie. "Whether or not he planned it, he is the reason my daughter is dead, bottom line. His actions directly caused her death."

Connie, it's crazy -- I am getting an email from my producer, who has notified me that while we've been talking right now, Marty reached out to him to say that he's innocent, that he had nothing to do with your daughter's murder.

The email goes on to say in part: "I was naive and trusting. I did nothing to Ms. Sunford. I had nothing to gain."

Do you have a message for anyone else who may have been involved, not yet charged, certainly not yet convicted, who may be involved in your daughter's death?

"Karma's a bitch, and once she's got your number, you never know when she's gonna come get ya," said Connie.

The mistress and Scott Sunford are no longer together after finding out the baby wasn't Scott's. The father was one of the mistress's ex-boyfriends.

Do you feel any guilt?

"Only when I feel like if I had just cut Marty out a lot sooner, it never would have happened."

How do you think you did in this interview?

"I didn't cry too much."

But we know the tears were fake.

"They weren't though."

People are going to watch this and say "Man, this woman is lying up and down."