Updated

An Indianapolis man will spend decades in prison after his conviction for a house explosion scheme that killed two neighbors, and prosecutors urged a judge Wednesday to make him eligible for life without parole at next month's sentencing.

Defense attorney Diane Black argued that prosecutors failed to prove the necessary aggravating factors that would make Mark Leonard eligible for the harshest penalty they were seeking. The debate included questions about the use of explosives, the fact multiple people were killed in the blast and that one of them burned to death.

Leonard, 46, was convicted Tuesday of murder, arson and conspiracy charges for the explosion that killed John "Dion" Longworth, 34, and his 36-year-old wife Jennifer.

Prosecutors introduced one piece of evidence during the second phase of the trial, a recording of the final moments of Dion Longworth's life captured by his security alarm company that called him after the blast. The recording wasn't played in court and had been ruled inadmissible for the first portion of the trial because St. Joseph County Superior Court Judge John Marnocha ruled it would be too prejudicial.

Marion County Deputy Prosecutor Denise Robinson wouldn't say specifically what could be heard on the recording.

"What I will say about the tape is you hear Mr. Longworth die," she said.

Prosecutors alleged Leonard was the mastermind behind the explosion, plotting with his then-live-in girlfriend Monserrate Shirley and his half brother Bob Leonard to blow up the home for $300,000 in insurance.

Black argued that Leonard wasn't the mastermind and that life would be too disparate a sentence from the one Shirley will receive. Black argued Shirley was just as involved, but the state had portrayed her as a victim unable to make a decision.

"It's a gender issue," Black argued. "The state played this card that was a woman in love, which is a ridiculous argument."

Shirley, who pleaded guilty to two conspiracy charges as part of a plea agreement, faces a possible sentence to 20 to 50 years in prison.

Marnocha said he would make a decision on whether Leonard would face life without parole before the Aug. 14 sentencing. He said the minimum sentence Leonard could face was 45 years and the maximum would be 1,488 years and the appropriate sentence "might be somewhere in between."

Robinson said she expects Leonard to spend the rest of his life in prison.

"If life without parole is not imposed in this case, the state will be arguing for a sentence that is in effect a life sentence," he said.