How throwaway comment snared a murderer: Arson suspect made detectives suspicious when he started talking about his pregnant wife who 'committed suicide' and they reopened investigation to prove he killed he

An Ohio man who murdered his pregnant wife three decades ago inadvertently caused investigators to reopen the case after he mentioned her alleged suicide 'outta the blue.'

Scott Purk was found guilty of murder and tampering with evidence in the death of his first wife, Margaret, in November 2015. He was convicted of arson and serving a separate prison sentence at the time.

Margaret had been 24-years-old and expected to give birth to their first child just days before her death in March 1985.

Prosecutors say Purk put a belt around Margaret Purk's neck and strangled her before trying to make it look like she hanged herself in their Akron apartment.

The death was originally ruled a suicide, and may have remained that way had Purk not spoken about Margaret's death to Lt. Ken Mifflin of the City of Stow Police Department years later.

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Scott Purk was convicted of murdering his wife, Margaret , nearly three decades after her death was ruled a suicide 

In a new NBC Dateline episode scheduled for Friday at 10pm ET, Lieutenant Ken Mifflin said that he was motivated to re-investigate Margaret's death while responding to a house fire. 

In March 2009, authorities dispatched to a fire at a residence Purk shared with his second wife and two children.

Purk, now 62, would later serve a 28-year prison sentence for arson related to insurance fraud, but at the time investigations had just begun.

Mifflin had been speaking to Purk about the house fire when the man unexpectedly brought up his deceased wife.

'Scott just outta the blue says to me, well, his first wife had committed suicide - in 1985. And she was pregnant, nine months pregnant,' Mifflin told Dateline.

Lt. Ken Mifflin : 'Scott just outta the blue says to me, well, his first wife had committed suicide - in 1985. And she was pregnant, nine months pregnant'

He added that he was caught off guard by the admission since it had nothing to do with the house fire or their conversation at the time.

'I was shocked at and - it made me wonder, "Okay, now I need to look into this." I I'm looking at someone who I believe is an arsonist,' said Mifflin.  'Now I'm wondering, "Okay, was he a murderer?"'

Following that conversation, authorities in Stow launched parallel investigations into Purk.

Mifflin would reexamine Margaret's alleged suicide in Akron, while now-retired arson investigator Jim Liedel would look into the fires in Stow.

Stow authorities launched a parallel investigation that saw Mifflin reexamining Margaret's death, while arson investigator Jim Liedel would look into the fires

Both Mifflin and Liedel told NBC Dateline reporter Josh Mankiewicz that they had a good working relationship throughout the case.

'He knows exactly what he's doing,' Mifflin said about Liedel.

But the two investigators would need to bypass a number of obstacles, including the fact that Margaret's death happened many years ago and that she died in Akron - an entirely different jurisdiction than Stow.

When asked by Mankiewicz how they approached Akron authorities, Mifflin said it was done with caution but they two departments are on good standing with each other.

'You have to approach it very carefully. But we have a good working relationship with the police department in Akron And I - you have to make the phone call,' said Mifflin.

Scott Purk (left and right) was serving a 28-year prison sentence related to arson when he was convicted of Margaret's murder 

According to Record-Courier, authorities had suspected Purk of setting his own home on fire for the insurance money, but did not have the evidence to convict him.

It wasn't until one year later, when Purk set fire to a duplex, that authorities noted that the fire resembled the one at Purk's home.

Mifflin told the publication that he visited the Bridgewater Parkway apartments where Purk was staying with his family.

There, he discovered a vital clue that linked Purk to the fires.

'That’s when things really started to unravel for him because that morning it was like 23 degrees, it was freezing,' Mifflin told Record-Courier.

'And every car in the parking lot by his apartment all had ice on it and frosted windows except for one car and it ended up being one of the Purk’s cars and that was the car he used to drive to commit the fire.'

'He wanted us to think there was a serial arsonist in the neighborhood,' Mifflin added.

It was around this time that the murder investigation in Akron hit a stride regarding the autopsy report.

Margaret was exhumed for a second autopsy that found she had marks consistent with ligature strangulation — not suicide by hanging as the first autopsy determined.

Mifflin: 'Had he not said anything, had he not told me anything, I would have had no reason to have looked into Margaret’s , let alone known that his first wife had died' Pictured: Scott Purk 

Photos from the 1985 autopsy clearly showed what happened, prosecutors said.  

Purk told police and paramedics that he used a knife to cut his wife down from the rope, then tried CPR to revive her, Hicks said.

Police and prosecutors didn't have the rope, the knife, the original crime-scene photos or the recording of the 911 call. 

'He really thought he was a smart criminal,' Mifflin told Record-Courier.

'Had he not said anything, had he not told me anything, I would have had no reason to have looked into Margaret’s , let alone known that his first wife had died.'