Siblings convicted of setting fire to Brockton home they were fostered in

BROCKTON − A brother and sister have been convicted on charges that they set fire to a Brockton home they were fostered in as children with the intent of killing those who were sleeping inside.

After a 10-day trial in Brockton Superior Court, a jury found Jonathan Jironvil, 26, of Worcester, guilty of three counts each of attempted murder, malicious destruction of property and witness intimidation.

His sister, Lucnalie Jironvil, 27, of Amherst, was convicted of three counts of attempted murder and one count each of arson and malicious destruction of property.

The siblings are scheduled to be sentenced on Thursday, June 22.

The charges stem from an incident that occurred early in the morning on July 18, 2019.

More:Siblings indicted on arson, attempted murder charges in Brockton

Firefighters responded about 2:30 a.m. to a report of a house fire at 66 Sinclair Road. Mary Louis, her daughter and her then-92-year-old mother were all inside the house when the fire broke out, but were able to escape without injury.

The ensuing investigation led authorities to the Jironvil siblings, who were previously in the foster care of Louis and lived at that Sinclair Road home.

According to court documents, Jonathan and Lucnalie Jironvil shared a goal of obtaining guardianship of their younger sister, who was also in the foster care of Louis.

Court documents revealed a lengthy "custody dispute" over the Jironvils' younger sister that led to violent behavior, harassing phone calls, broken windows and a DCF worker to claim there was something "mentally wrong" with the siblings.

"Louis immediately informed Brockton police they believed Jonathan and Lucnalie were responsible for the fire," Mass. State Police Sgt. Thomas M. Berteletti, who is a fire investigator assigned to the Office of the State Fire Marshal, previously wrote in a police report.

Investigators learned that a camera had been put up facing the home in July after the first incident of vandalism, when a large rock was thrown through the front bay window of the home in June. Surveillance footage showed a small sedan pass in the front of the home slowly, then captures a flickering light that grows in intensity on the right side of the home.

"Two individuals wearing hoodies are observed running away from the right side of the home as the flicking light continues and grows brighter," Berteletti wrote.

Police say they learned Lucnalie Jironvil owned a Honda Civic, similar to the vehicle seen in the video. Records obtained by the state Department of Transportation confirmed her car was active on the road between the night of July 17 and the morning of July 18. Investigators say they determined the car was in the Brockton area at the time of the fire. They also used phone records after obtaining a search warrant.

"Investigators sought call data and location data for the period of time shortly before and after the fire at 66 Sinclair Road," Berteletti wrote. "The T-Mobile records reflect that both Jonathan and Lucnalie were in Brockton at the time of the arson."

The case was prosecuted by Assistant District Attorney Alexander Zane.

Enterprise senior reporter Cody Shepard can be reached at cshepard@enterprisenews.com.