Jean Marie Louis (left) and Mark W. Sargent (right) were arraigned in Brockton District Court today on arson charges. They pleaded not guilty to all charges and were ordered held without bail pending a dangerousness hearing.
Jean Marie Louis (left) and Mark W. Sargent (right) were arraigned in Brockton District Court today on arson charges. They pleaded not guilty to all charges and were ordered held without bail pending a dangerousness hearing.
George Rizer for The Boston Globe

BROCKTON — A prosecutor said today that a 45-year-old Middleborough man has been linked to 24 fires in an arson spree in Southeastern Massachusetts.

Mark Sargent is facing arson charges in a West Bridgewater fire on Wednesday night. He was arrested along with his stepson, Jean Marie Louis, 23. Both appeared for arraignment today in Brockton District Court, where they were ordered held pending a dangerousness hearing set for Feb. 6.

The two men were arrested Wednesday night after a small fire was set at a commercial building under construction in West Bridgewater and State Police, who had secretly attached a GPS tracking device to Sargent’s car, learned the men had been near the property before the fire began.

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In court today, a Plymouth County prosecutor said authorities now have evidence linking Sargent to 24 of 38 arson fires that have swept through the southeastern corner of the state in the past several months.

Authorities said that Sargent was stopped by police on Dec. 19, shortly after someone poured gasoline into a boat stored at a Marshfield boatyard, setting it afire. Sargent, who appeared nervous, told police he was “just driving around’’ the area when they stopped him.

On Dec. 21, after obtaining a court order, State Police attached a GPS tracking device to a Toyota Highlander that Sargent was known to drive. They monitored the vehicle driving near six arson fires at the times the fires broke out, authorities said.

Earlier this month, Sargent traded in his Highlander for another car, a Subaru Outback, which he and his stepson were arrested in Wednesday night. It also had a tracking device installed.

According to authorities, they also investigated Louis and discovered that he used his credit card at a Cumberland Farms store in Halifax on Nov. 26, the same day an arson fire damaged a Monponsett Street building in that town.

According to authorities, Sargent allegedly used a fireplace starter log and gasoline to start fires.

A motive for the arson spree was not disclosed.

State Fire Marshal Stephen Coan and Plymouth District Attorney Timothy J. Cruz were planning a news conference this afternoon to discuss the case.

State Police, in a report filed in court, described tracking the two men and then arresting them following the fire in West Bridgewater Wednesday night.

“Shortly after the fire was reported, the suspect vehicle ... was observed through GPS tracking to have been by the site of the [West Bridgewater] fire multiple times and actually stopped in the vicinity of the fire for a period of approximately 10 minutes,’’ said a State Police report written by Trooper Eric D. Desrochers.

Once the West Bridgewater fire was extinguished, State Police arson investigators recovered remnants of a fireplace starter log and collected soil samples after their accelerant-sniffing dog, Damian, reacted to areas near the fire’s point of origin, State Police said.

According to State Police reports filed in court, the series of events that ended with the arrests began when a West Bridgewater man stepped outside of his house to have a cigarette. He spotted the small fire at 457 South Main St., a building under construction, and alerted authorities.

The man also reported seeing a red car speed away from the scene at a high rate of speed, a vehicle he believed may have been a Honda Civic.

State Police later interviewed two other neighbors who described seeing a man wearing a dark sweatshirt walk away from the property in the pouring rain shortly before the fire broke out.

When he was arrested, Louis’s shoes were covered with mud from the washed-out building site and his pants were spattered with dirt, State Police said. A pair of gloves, reeking of gasoline, were found in the front pocket of Louis’s black, hooded sweatshirt, State Police said.

The small blaze broke out at 9:35 p.m. Wednesday and was confined to a small area of the building.

Authorities said damage was estimated at less than $5,000. No injuries were reported.