Richmond Hill Trial: Fire investigator says gas leak was intentional

Richmond Hill explosion scene

IFD Lt. Mario Garza started the week off by returning to the stand and saying the leak of gas into Monserrate Shirley's home was intentional as the prosecution began moving from basic crime scene evidence into the "origin and cause" of the explosion.

After inspecting evidence at the scene, Lt. Garza was able to rule out an airplane crash, meth lab explosion and weather as possible causes of the explosion. The gas company's testing then ruled out a gas leak in the company's pipes as well as "fugitive gas," which is when gas escapes from another location to cause a problem elsewhere.

His next hypothesis was a "non-jurisdictional" gas explosion, meaning it was caused by natural gas, but the source was in a section of the gas piping considered to be the property of the homeowner. He could tell Monserrate Shirley's home was the center of the explosion because blast patterns shot from that address in a full 360 degree fashion out into the neighborhood. Further, "anchor bolts" that hold the wooden frame of the house together as a cohesive piece and anchor it to the concrete foundation were bent outward from the interior of the home, indicating a blast from inside pushed them outward.

"Even someone without training would know this house exploded," he said of the blast scene.

All evidence was picked up by hand and examined, never scooped up by a machine. Firefighters were even sent onto the roofs of neighboring homes to check for potential evidence that may have landed there as opposed to the ground. Later in the investigation, though, they did use sifters custom-made for this investigation that helped to sift out dirt and other non-material matter, leaving only potential pieces of evidence for investigators to look at.

When searching through the debris, searchers found several remote controls, but no televisions from the Shirley home.

He also didn't find what has been described as one of the family's most prized possessions. As part his investigation, Lt. Garza got photos from previous real estate listings from when Monserrate Shirley tried to sell the home, and used those photos for comparison to help identify pieces of debris his team found on the scene. Based on that visual assessment, he does not believe they ever found the portrait of Shirley's daughter, Brooke, which hung above the fireplace.

Ignition source

They did, however, find several potential ignition sources, including candles, a thermostat, the ignitor for the furnace and a metal canister that showed signs of having exploded while inside the microwave. Investigators also found some small fireworks, but Lt. Garza said there were not nearly enough to be considered a potential ignition source in this case.

The metal canister was considered the most likely ignition source given the damage both to it and to the microwave itself, however Lt. Garza admitted it was impossible to know for sure which potential ignition source was ultimately responsible for the explosion.

"Something exploded inside the microwave, is the easiest way to say it," he clarified.

He also said the fact that there were multiple possibilities does not mean any of those options become any less likely to be the official ignition source, and the explosion could have actually been triggered by more than one.

Defense attorney Diane Black then implied multiple ignition sources could also be a sign the intent was merely to start a fire, not an explosion. Lt. Garza said that may technically be possible, but the combination of multiple ignition sources along with the large amount of gas pumped into the home make it a more logical assumption the intent was for an explosion.

Lt. Garza's team found the manual for the microwave in a debris pile near what was the kitchen area of the home. That manual showed that the microwave could be programmed to start on a delay of up to 24 hours. That means if the microwave was what triggered the explosion, it had to have been programmed to do so no earlier than Friday around 11:00 p.m. Black said in cross-examination that both Mark Leonard and Monserrate Shirley were at the Hollywood Casino in Lawrenceburg Friday night.

Final report

Lt. Garza spent roughly 20 days on the scene over the course of November and December. Meanwhile, IMPD conducted a simultaneous, but completely independent investigation into the explosion. Almost a year after the explosion, and after charges were filed against Mark Leonard, Lt. Garza listened to all 911 calls and recordings of IMPD's interviews to help write his final report on what caused the explosion.

He came to the conclusion it was caused by natural gas. He compared a natural gas explosion in any situation to dropping a rock into a body of water: it creates ripples going out in every direction, but there is also some bounce back caused by reverse pressure so that some of the force actually goes back toward the source of the explosion. Lt. Garza said he saw evidence of all that at the scene, with Monserrate Shirley's home as the epicenter.

Given that, there were three potential sources of gas inside the Shirley home:

  1. the water heater
  2. the furnace
  3. the fireplace log lighter

Even though the furnace was moved by the force of the explosion, knocked over and found underneath a lot of debris, the gas lines feeding it were all still in tact, so it was ruled out as a source.

The water heater's lines were also all attached and all safety equipment was still in place. All of the damage to the unit itself was also deemed to be the result of an external fire as opposed to a sign of an internal fire that could have caused an explosion, so it was also ruled out as a source.

Meanwhile, all pipelines leading to the fireplace log line were in tact, and the Dante valve on the log line was missing. The Dante valve is the only safety feature the fireplace has, according to Lt. Garza. He said there is no logical reason to take it off because doing so meant there was nothing to stop the gas from flowing out of the line and into the house.

As others have testified, the gas line's step-down regulator was not only missing but had been replaced by a piece of straight pipe, meaning the missing regulator was not simply blown out by the force of the explosion. This was both a sign the gas leak was intentional as well as evidence that gas would have been flowing into the house at a faster rate than what the log line would normally produce.

There are four cause classifications that can be applied to a fire or explosion:

  1. incendiary (intentional)
  2. accidental (unintentional human error or appliance malfunction)
  3. natural (lightning strikes)
  4. undetermined

Lt. Garza ruled this explosion as an incendiary incident.

After all debris was removed, they washed down the floors to see if any fire patterns could be seen. They then took core samples - circular chunks out of the foundation concrete that were sent off for testing. Several samples were taken in what appeared to be a fire pattern to be tested for ignitable liquids like gasoline.

Two samples came back positive for gas - one in the living room and one in the kitchen.

While putting together his origin and cause report, Lt. Garza listened to witness testimony from IMPD's investigation. One of those witnesses testified that Mark Leonard and his half-brother spoke with an employee of Citizens Energy at a bar about how much natural gas it would take to fill a house and asked about regulators.

In the end, Lt. Garza concluded that the natural gas was intentionally released into the house, resulting in an explosion that caused the deaths of John Dion and Jennifer Longworth.


When it was her turn to question Lt. Garza, Defense Attorney Diane Black also reminded the court that for the first several hours after the explosion, firefighters were more concerned with suppressing the fire and saving lives than maintaining the integrity of a crime scene, which means some pieces of evidence may not have been collected where they actually landed - including the microwave. Lt. Garza confirmed that during that initial period, some of the pieces of the microwave were moved because children's toys were located nearby. He worried that meant they may have missed someone who was still trapped so he moved the microwave pieces to make room for front-line rescuers to do another search of the area.

Police investigation

Det. Sgt. Jeffrey Wager is the late shift supervisor on IMPD's homicide unit, and was the lead investigator assigned to this case. He also witnessed the county coroner's autopsies of the Longworths.

After identifying Monserrate Shirley as the homeowner, he looked into where she and Mark Leonard were and found out they had been at the Hollywood Casino in Lawrenceburg. He also learned Shirley's daughter Brooke had been staying at someone else's house and the family cat, "Snowball," was at Barkefellers kennel.

IMPD Det. Randy Cook took the stand next. He said he felt the explosion at his own home, roughly 4-6 miles away. He said it shook and rumbled the home while he watched a Notre Dame football game. He immediately started getting ready, assuming he would be called to the scene. Sure enough, his pager went off as he was leaving his house, giving him the address.

Upon arriving at the scene, he could only describe it as, "A lot of devastation."

He was directed by another officer to go to a nearby elementary school where residents had been sent in order to gather names, addresses & phone numbers of those residents. As he was getting ready to leave around 3:00 a.m. after speaking with everyone else there, he saw Leonard and Shirley walking toward his car in the school parking lot. Since they were already outside, he spoke with them in his car. Det. Cook sat in driver's seat with Leonard in the front passenger seat and Shirley in the back passenger seat.

Det. Cook said Leonard did most of the talking while Shirley sobbed. Leonard told him they'd just come back from the casino after getting calls from friends about what had happened. He said they'd heard there may have been a plane crash, but also said they'd smelled gas in the house 1-2 weeks beforehand and also smelled it in the neighborhood. He also said he'd had some issues with the thermostat and had to have it changed recently.

Cook said Leonard brought up the gas on his own - he had not asked Leonard about it.

ATF Special Agent Dan Shirley was one of the agents who helped take statements from witnesses. He also helped execute a search warrant at Bob Leonard's trailer. He did not collect any evidence himself, but said he saw a set of golf clubs be removed from the home.

The last thing he was asked to do for the investigation was help IMPD interview Gary Thompson and Glenn Hults - the 4th and 5th suspects arrested in this case.

Hollywood Casino

The final witness of the day was Travis Bell, a DJ at Hollywood Casino in Lawrenceburg - one of the state's riverboat casinos, and the casino Leonard and Shirley claim to have been at on the night of the explosion.

Bell testified he was working on the night of the explosion - something that sticks out to him because he normally only works in an 80s themed nightclub at the casino. That night, though, he was playing for the full house. It also sticks out to him because Mark Leonard and Monserrate Shirley used a bartender at the casino to flag him down while he was on stage so they could talk to him in person.

When Bell finally agreed to put on a long song and step off stage to see them, he testified they told him it was their anniversary and asked him to make a mention while he was on stage. He also said Leonard insisted he knew him from the south side of Indianapolis (Leonard said he went to Southport while Bell went Perry Meridian). Bell said he did know Bob Leonard before that night, but had no memory of having ever met Mark Leonard.

Bell testified Leonard did most of the talking, but he did shake hands with and introduced himself to Shirley. He did not see them leave, but did recall seeing them at the bar for at least another hour after talking to them, putting them at the casino from at least 9:00 - 10:00 that night.

A few days later, Bell was at a barbeque restaurant in Indianapolis (he still lives on the south side, roughly 4 miles from Richmond Hill) and saw Leonard and Shirley's pictures come up as a local newscast aired on one of the restaurant's televisions. He soon called IMPD detectives and told them what he knew.

Monserrate Shirley

She still hasn't taken the stand, but Monserrate Shirley was once again the subject of debate Monday morning in the courtroom.

Defense attorneys have previously tried to mention Shirley's alleged infidelity, even claiming that at one point, she blackmailed a doctor with whom she'd had an affair. They argued bringing this to the jury's attention would go to prove her ability to manipulate situations and the men around her, but prosecutors said her personal indiscretions were not relevant to this case.

The judge sided with prosecutors, and granted a preliminary motion to limit any questioning along those lines.

Prosecutors told the judge Monday afternoon they plan to call Shirley to the stand on Wednesday. Tuesday will be more witnesses from the casino, as well as the Indiana Gaming Commission.