I-Team: Slain Yarmouth Cop Faced Accused Killer In Court, Testified In Dismissed Case

YARMOUTH (CBS) - Before he was shot and killed in the line of duty, Yarmouth police officer Sean Gannon had already faced the career criminal now charged with his murder.

Chilling audio obtained by WBZ-TV's I-Team reveals Gannon testified last year in a domestic violence case that would've put Thomas Latanowich behind bars again.

Instead, the judge ultimately dismissed the case, allowing the man with a lengthy criminal record to remain free.

A year later, authorities say the two men would meet again during a fatal encounter as Gannon tried to arrest Latanowich on an outstanding warrant.

"This is a tragic irony," said WBZ-TV legal analyst Jennifer Roman, a former prosecutor. "There is really no other way to describe this."

In October 2016, Latanowich faced criminal charges that included strangling a pregnant woman and vandalizing her property.

The serious allegations occurred while Latanowich was on probation for a previous stint in prison. A conviction would likely land him back behind bars for several years.

"My boyfriend just choked me and slashed the tire on my car," the woman said in a 911 call played in court.

However, there was a problem - the alleged victim did not want to cooperate with prosecutors, choosing instead to invoke her Fifth Amendment privilege.

During the February 2017 hearing, Barnstable District Court Judge Thomas Barrett asked, "You understand that if you don't testify in this case, the charges may well be dismissed. Do you understand that?"

"Yes, your honor," the woman responded.

Prosecutors tried to press forward by calling the first police officer to respond to the scene that day - Officer Gannon.

"She was able to tell me that she was attacked by her boyfriend. She described Tommy as her boyfriend to me," Gannon recalled. "The conflict occurred inside her apartment. It was over a cell phone dispute."

Gannon told the judge he noticed red marks on the woman's neck and a slash in her vehicle's tire. He then searched the neighborhood unsuccessfully for any signs of Latanowich.

"She told me that Tommy got on top of her and began strangling her after he pushed her down on the floor," Gannon testified. "She was able to fight him off. At that point, he took a knife, went out and stabbed her front left tire and ran away on foot."

However, Gannon's account was not enough to rescue the case. The judge ruled the alleged victim's statements to the Yarmouth police officer and her 911 call could not be admitted as evidence.

"With this individual invoking the Fifth Amendment, the Commonwealth has to go with the hand it's dealt, unfortunately," Judge Barrett said. "So the matter will be dismissed for lack of prosecution."

After sharing a transcript of the courtroom audio, the I-Team asked Roman if it was reasonable for the judge to dismiss the case.

Roman explained that without victim cooperation, the other evidence was considered hearsay. The only exception was if prosecutors could prove the woman was still in a state of emergency when she called 911 and spoke to police. According to the courtroom audio, the judge did not believe they met that legal threshold.

"Under those circumstances, the judge definitely made a judgment call, but it was well within the rules of evidence and his discretion. It wasn't unreasonable," Roman said.

Latanowich also escaped another criminal conviction later that year when Barnstable County prosecutors dismissed stabbing charges against him in April 2017.

Audio the I-Team obtained of that court hearing indicates the case also fell apart because of inadmissible evidence and a lack of victim cooperation.

"It's a serious case, but I can't justify it continuing at this point," the prosecutor told the judge.

The details are likely to add to the mounting frustration already expressed by law enforcement about how a man with more than 100 criminal charges on his record had managed to stay out of prison.

"This didn't end up the way we would like to see it happen because of the end result," Roman said. "We can't predict that. We can say the guy is escalating and is a bad apple, but our system is a reactive one. You have to do something before we can press charges against you and take appropriate action."

Latanowich is now being held without bail on the murder charges and some state lawmakers are calling for reinstatement of the death penalty for criminals who kill police officers.

Ryan Kath can be reached at rkath@cbs.com. You can follow him on Twitter or connect on Facebook.