INDIANAPOLIS – A Marion County prosecutor said Monday he won’t seek the death penalty for three people charged in a deadly Indianapolis house explosion because a jury is unlikely to choose that option.

Prosecutor Terry Curry announced he will seek life sentences without parole if a jury convicts Monserrate Shirley, her boyfriend Mark Leonard and his brother, Bob Leonard. All three face murder, arson and conspiracy charges in the Nov. 10 blast that destroyed dozens of homes and killed two people.

Investigators say Shirley and the Leonards intentionally created a gas explosion in Shirley’s home in hopes of collecting insurance money. Thirty-three homes in the Richmond Hill subdivision were damaged so extensively they had to be demolished.

A microwave set to start on a timer sparked the explosion in Shirley’s gas-filled home, Curry said. Investigators determined that a gas fireplace valve and a gas line regulator in the house were removed. Investigators believe the three also tried but failed to blow up Shirley’s home earlier.

John and Jennifer Longworth died after the explosion ignited another explosion and resulting fire at their house.

Curry also announced new charges. The state has filed a motion to add a felony count of arson against all three defendants for damage to houses that did not require demolition.