The man whom investigators called the mastermind of a southside explosion that killed two people and damaged dozens of homes should have known the scheme could kill people, even if that wasn’t his intent, a prosecutor told jurors as the trial began.

Mark Leonard, 46, is charged with murder, 46 counts of arson, two counts of conspiracy to commit arson and one count of conspiracy to commit insurance fraud. The Nov. 10, 2012, blast killed 36-year-old Jennifer Longworth, a second-grade teacher at Southwest Elementary School in Greenwood, and her husband, John Dion Longworth, 34, a product developer for a consumer electronics company.

In her opening statement, Marion County Deputy Prosecutor Denise Robinson said she isn’t going to argue Leonard intentionally killed the Longworths, who lived next-door to Leonard’s then-girlfriend, Monserrate Shirley. But Leonard should have known deaths were possible when he planned to use natural gas to blow up Shirley’s house, causing a blast that was felt in Johnson and Shelby counties.

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Leonard’s public defender, Diane Black, said her client intended to start only a small fire.

“This was a stupid and selfish insurance fraud that went horribly wrong,” Black said.

Both sides gave their opening statements Monday for the start of Leonard’s trial. St. Joseph Superior Court Judge John Marnocha spent 25 minutes reading the charges against Leonard in a videotape played in the courtroom.

Robinson told the jurors they will hear from many people who lived in the Richmond Hill neighborhood on the southside, where nearly every house sustained damage, and the impact the explosion had on them.

“This was not a gas leak. This was not an accident. This was a substantial act,” Robinson said. “This wasn’t a house that exploded. This was much more than that.”

Leonard and four others charged in the case were motivated by a desire to collect $300,000 from an insurance policy on the contents of the house, she said.

“This is about greed. This is about money. This is about wanting to get that money,” Robinson said.

Black told the jury to consider not just the results of what happened but who is responsible for what happened. The results of the explosion are “obvious and tragic.” Children who live in the neighborhood can’t sleep well at night, and the neighborhood will never be the same, she said.

“It’s going to cry out to you to mete out the strongest punishment you could based on the results,” Black said. “But what we must look to, what we’re going to struggle with, is the responsibility.”

Some of the responsibility goes to Shirley, who reached a plea agreement with prosecutors in January, Black said. Shirley was allowed to plead guilty to two counts of conspiracy to commit arson, in exchange for her agreeing to testify against Leonard and the others charged in the explosion.

Shirley didn’t say a word about Leonard being the person behind the plot until she struck a plea deal, Black said.

“She was desperate, and this is how she dealt with it,” Back said.

David Shircliff, another attorney for Leonard, told potential jurors during the selection process that Leonard would not testify during the trial.

The trial was moved to St. Joseph County because of widespread media coverage of the case. The trial is expected to last four to six weeks with about 175 witnesses expected to be called.