Dateline: Deadly Obsession - 5 harrowing details about Mike Sisco and Karen Harkness' murders, revisited

NBC Dateline's recent episode, titled Deadly Obsession, was a harrowing case that spanned more than two decades. Mike Sisco and Karen Harkness had been dating for years and were murdered in July 2002 in their Kansas home. There was no scientific or circumstantial evidence that would point to a killer, but two decades and three trials later, Dana Chandler, Mike's ex-wife, was convicted as the killer, based on the family's statements, her shady alibi, and her prior conduct.

Here are 5 harrowing details about the double homicide featured on the Dateline episode Deadly Obsession, which aired on April 4, 2025.

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5 Harrowing Details about Mike Sisco and Kare Harkness' murders, as seen on Dateline: Deadly Obsession

Mike Sisco was convinced that Dana Chandler would kill him

Even though Mike and Dana had been married for 15 years, they went through a bitter divorce, which took almost four years to be finalized. Even after it was finalized, Chandler continued to stalk and harass Mike. Dateline revealed that this behavior got even worse after Mike started dating Karen and seemed to be moving on. Chandler had a drinking problem and troubled Sisco with frequent calls and bizarre visits. Cathy Bates, Mike's sister, once woke up in the middle of the night, when she was staying at her brother's, to find Dana outside his home in his backyard, jumping on his trampoline.

Nine days before the murder, Mike Sisco was on a fishing trip with his brother-in-law Mark Boots, and told him:

"Mark, you're gonna wake up and find me dead. And I want you to know who did it, Dana Chandler."

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Dateline revealed that Dana Chandler had an alibi, but it was shaky at best

Even though Mark's family, and even his and Dana's children, were convinced that their mother, Dana Chandler, was the one who had murdered Mark and Karen, there was no scientific evidence that would place her at the scene of the crime. According to Chandler, on the night of the murder, she was in her home in Colorado, hours away from Mark and Karen's home, and the next day, she drove through the mountains.

However, Chandler's business associate, Jeff Bailey, revealed in his testimony that Chandler told him that she slept in her car in the mountains on Saturday, the day of the murder. No footage from the CCTV cameras at the mountain's entry or exit point recorded her car passing. Additionally, Chandler's phone was also untraceable for 27 hours during the time of the murder. Her daughter, Hailey Seal, Dateline revealed, accused Chandler of preventing her phone from being tracked to the crime scene by turning it off.

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Dateline revealed that the prosecutor who argued the case against Dana Chandler in the first trial was disbarred when the trial was overturned

During the first trial, where Dana Chandler was tried for the double homicide, Kansas prosecutor Jacquie Spralding managed to get a guilty verdict from the jury, but she made a few statements that were later revealed to be completely false, leading to her being disbarred. One of the reasons why she was disbarred was because she made a statement that Mike had a court order against Dana, a "protection from abuse" order, and that Dana had violated that order.

However, it was later found out that no such protection from abuse order was ever found, and this was blatant "prosecutorial misconduct," as revealed on Dateline. The court agreed to overturn Chandler's conviction on the grounds of unfairness and even went on to disbar Spradling, describing her actions as "intolerable acts of deception."

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Dateline revealed that Hailey Seel started to record her phone calls with her mother

Three years after the murder, in 2005, there were no leads on the double homicide, and it was officially a cold case, but the family members were still looking to figure out the truth. Hailey Seel, Mike and Dana's daughter, started recording her conversations with her mother, hoping for some sort of confession on the phone calls.

Dateline revealed that in one of these phone calls, Dana insisted, trying to convince her daughter that she had nothing to do with the murders, but admitted to having thought about killing Mike, to having violent thoughts about him. This phone recording was used as major proof in establishing Chandler's motives in the trials, along with Hailey's testimonies against her mother.

DANA CHANDLER (recorded conversation): "I said I could kill him. You ever think about killing him?"

HAILEY SEEL: "No, but —"

DANA CHANDLER: "I did."

HAILEY SEEL: "But —"

DANA CHANDLER: "Honestly, I can say I did."

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A gas station clerk was 70 percent sure she saw Dana Chandler in Kansas, halfway between Denver and Topeka

The one thing that made the state's case against Dana Chandler exceptionally weak was the fact that there was no eyewitness or proof that could put Dana Chandler in Topeka, Kansas, on the 6th or 7th of July 2002. The closest that the state came to finding an eyewitness was Patty Williams, a gas station clerk in WaKeeney, Kansas, who thought she might have seen Dana on the night of 6th July.

Patty was shown Dana's picture, and she said she was 70 percent sure she saw Dana in the gas station. She was also shown an array of pictures (people who looked similar to Chandler and Chandler's pictures together), and she picked out Chandler's photo from the array; however, this should've been done before the original interrogation where she was shown a picture of Chandler herself for it to have any weight in court.

However, by the time the case went to trial in 2012, Patty Smith had died and could not have testified.

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These were 5 exceptionally disturbing facts of the 2002 double homicide case against Dana Chandler. To know more, read here.

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