The Richmond Hill Explosion: Inside the Insurance Fraud Plot That Killed 2 Neighbors

Shortly after 11 p.m. on November 10, 2012, an explosion tore through the Richmond Hill subdivision on the south side of Indianapolis.

The blast leveled one house and badly damaged dozens of others, scattering insulation, wood and household debris across the neighborhood. Residents who survived emerged to find homes burning and others reduced to rubble.

Monserrate Shirley’s home sat at the center of the destruction, but the two people killed were her next-door neighbors: 36-year-old Jennifer Longworth and her 34-year-old husband, John “Dion” Longworth.

Jennifer died in the initial explosion. Dion survived the blast but became trapped in the basement of their burning home, where he died from smoke and hot gas inhalation in addition to severe burns.

Seven other people were injured. About 80 homes sustained damage, and the destruction was estimated at more than $3 million.

What initially appeared to be a catastrophic accident was eventually exposed as an intentional explosion, set as part of an insurance fraud scheme that went far beyond what its participants claimed they intended.

Shirley owned the home where the blast originated. She lived there with her boyfriend, Mark Leonard. Prosecutors said Leonard devised a plan to destroy the house so Shirley could collect approximately $300,000 through her homeowners insurance policy when the couple found themselves in financial trouble.

Investigators discovered Shirley and Leonard had approximately $63,000 in credit card debt, were involved in bankruptcy proceedings and had taken out a second mortgage on the home. Leonard had also reportedly lost about $10,000 at a casino weeks before the explosion.

Leonard recruited his half brother, Robert “Bob” Leonard Jr., to help carry out the plan. Shirley later testified that Robert was promised $10,000 for his assistance.

According to prosecutors, the conspirators tampered with the house’s natural gas system. Investigators found that a step-down regulator had been removed and replaced with a straight piece of pipe, allowing gas to enter the house at a much greater volume than normal.

On the day of the explosion, a gas line connected to the fireplace was opened to fill the home with gas, and a microwave was programmed to activate after the conspirators had left. Prosecutors argued that the microwave produced the flame that ignited the accumulated gas. During Mark’s trial, a fire investigator testified that he reproduced the setup and observed a burst of flame capable of igniting gas in the room. 

The resulting explosion was powerful enough to devastate much of the subdivision.

The November 10 blast was not the group’s first attempt at burning down the home.

Investigators learned that the conspirators had tried to destroy the house on two earlier weekends. Each time, Shirley and Mark left town for a casino.

Shirley’s daughter was sent to stay elsewhere, and the family cat was boarded. Personal belongings were also removed from the house. The same precautions were taken before the final attempt.

Another participant, Gary Thompson, assisted with preparations during the failed attempts but later backed out.

Authorities initially investigated whether the blast had been caused by an appliance malfunction or utility failure. By November 19, however, authorities began treating the explosion as a criminal investigation.

The missing gas components were among the most important pieces of physical evidence. Investigators also traced a white van seen at Shirley’s house on the day of the explosion to Robert.

When police interviewed Mark Duckworth, a longtime friend of Mark Leonard, Duckworth testified that, days before the blast, Mark Leonard claimed his house had already exploded after “tsunami winds” affected the fireplace and said he expected to receive $300,000. Leonard later told Duckworth that he made up the story.

Shirley ultimately agreed to cooperate with prosecutors. In 2015, she pleaded guilty to two counts of conspiracy to commit arson and testified against the Leonard brothers.

A jury convicted Mark in July 2015 on all 53 charges against him, including two counts of murder and multiple arson and conspiracy insurance fraud charges. He received two consecutive life sentences without parole, plus 75 years.

Robert was convicted on all 51 charges against him, including felony murder, in February 2016. He received two consecutive life sentences without parole, plus an additional 70 years. The Indiana Supreme Court later upheld his sentence.

Shirley received the maximum sentence permitted under her plea agreement: 50 years in prison. At sentencing, Judge Sheila Carlisle said Shirley had protected her daughter, cat and possessions from the house but had done nothing to protect her neighbors.

Thompson pleaded guilty to one count of conspiracy to commit arson and was sentenced to 30 years, with 10 years suspended. Glenn Hults, who knew about the plan and helped keep Shirley’s daughter away from the house, pleaded guilty and received three years for assisting a criminal.

Robert remains sentenced to life without parole. Shirley is serving her decades-long sentence.

Mark died at age 48 in an Indianapolis hospital on January 30, 2018, after becoming ill while incarcerated. The Indiana Department of Correction said he died of natural causes.

His death came less than three years after he was convicted for engineering the insurance scam that killed the Longworths and transformed an ordinary Indianapolis neighborhood into the scene of one of the city’s most destructive crimes.