(Reuters) - Prosecutors on Thursday charged a fourth person with murder and arson in connection with a 2012 home explosion that killed a couple next door and damaged scores of homes in an Indianapolis neighborhood.
Gary Thompson, 44, who denies causing the explosion that killed neighbors John and Jennifer Longworth, was charged with two counts of murder, conspiracy to commit arson and 46 counts of arson, Marion County Prosecutor Terry Curry said.
Monserrate Shirley and brothers Bob Leonard Jr. and Mark Leonard had been charged previously with murder and arson in the Nov. 10, 2012, explosion that destroyed the home where Shirley lived with Mark Leonard.
The explosion and fire burned the Longworth's home next door.
Curry said Shirley provided information that aided the case against Thompson. Shirley has agreed to plead guilty to two felony counts of conspiracy to commit arson and other charges against her were dropped.
Thompson, who had worked for Mark Leonard for several years, told detectives the man had offered him $5,000 to pour six cans of gasoline inside Shirley's home to start a fire on Oct. 27, 2012, according to a police affidavit.
Thompson backed out, saying he got scared, but he then helped Leonard stuff a chimney in the house with cardboard to block air flow and installed a timing device in the house that would cause natural gas to ignite, the affidavit states.
An attempt to set fire to the house failed the next weekend, but the house exploded on Nov. 10, 2012, while Shirley and Mark Leonard were away.
Prosecutors previously said that personal property insurance on the house had been raised to $304,000 and photographs and personal financial records were removed before the explosion.
Investigators believe a programmable microwave that exploded from the inside out was the source of ignition and valves that regulate natural gas into the home and to a fireplace were removed, allowing gas to build up over hours, Curry has said.
Prior to the explosion, Bob Leonard and Mark Leonard had consulted a Citizens Energy Group employee on how much gas it would take to fill a house, Curry said.
Thompson is scheduled to appear in court on Friday.
(Reporting by Kevin Murphy in Kansas City, Missouri; Editing by Mohammad Zargham)