Monserrate Shirley, 47, her boyfriend, Mark Leonard, 43, and his half brother Robert "Bob" Leonard Jr., 54, are each charged with multiple counts of felony murder, conspiracy to commit arson and arson for the Nov. 10 attack. The three were arrested and charged Friday.
Investigators said the three suspects conspired to blow up Shirley's home to collect about $300,000 in insurance money, the Indianapolis Star reported. The explosion, however, destroyed several homes, damaged more than 80 and killed Jennifer and John Longworth, Shirley's next-door neighbors.
The three appeared before Judge Sheila Carlisle in Marion Superior Court.
The Leonard brothers both asked for court-appointed attorneys, while Shirley had already hired a lawyer.
Jordana Brewster on Paul Walker: 'He was an enormous presence in my life'
Exploding whale video goes viral on Internet