Brian McCann of Hermon, who was already on probation as a juvenile in Maine, faces a stack of adult charges in Massachusetts after breaking into the Hermon town garage, stealing a sheriff’s cruiser and driving almost to Boston before being caught on Saturday.

Because of an ignition problem, the keys were kept in the cruiser’s starting switch, according to Penobscot County deputy sheriffs. But they doubt McCann knew the keys were in the ignition before he jimmied one of the bay doors at the Hermon town garage and staved in the cruiser’s side sometime between 2 and 4 a.m. Saturday.

Though the 17-year-old McCann is a juvenile under Maine law, in Massachusetts he is considered an adult. He is scheduled to face seven charges in Chelsea District Court outside Boston this morning that range from failing to stop for a police officer to assault and battery with a dangerous weapon.

Sgt. Ronald Sieberg of the Massachusetts State Police said that at the end of a short chase in the towns of Revere and Everett, McCann crashed into a parked car and then, in an escape attempt, backed into the cruiser that pursued him. This led to the assault and battery charge.

After his arrest, McCann was held in the state police barracks in Revere pending his court appearance.

Penobscot County deputy sheriffs have no definite motive for the theft. However, Hermon Senior Deputy Bill Laughlin said that McCann might have gotten wind that he was a suspect in an incident that occurred at the Bangor Mall on Friday.

A note left at the town garage indicates that the writer didn’t care if he got “25 years to life” in prison, said Laughlin, who would disclose no other details about the note except that it was written in the style of highway graffiti.

The cruiser, with Penobscot County Sheriff’s Department markings, was part of the department’s constable-deputy program, where towns hire the constables and buy the cruisers, and the county provides supervision and training.

The thief jimmied open one of the two bay doors into the garage, according to Laughlin. The door had been causing problems and attempts had been made to repair it.

Inside the garage, the thief broke the back windows of the cruiser with a metal bar. A second cruiser in the garage was untouched.

The sheriff’s department learned just before 9 a.m. Saturday that one of its vehicles might have been stolen after a motorist notified the Maine State Police that a cruiser with Penobscot County markings and broken windows was traveling at high speed south on the Maine Turnpike through Kennebunk.

According to Glenn Ross, chief deputy sheriff in Penobscot County, a second alert from the state police came in a short time later saying that one of the department’s cruisers had just gotten gas at the Two Sons Mobil in Kittery and had driven off without paying.

About the same time, the Hermon break-in was discovered, Ross said.

State police in New Hampshire and Massachusetts were told to be on the lookout for the cruiser.

It was spotted in both states before being sighted at about 9:15 a.m. on Route 1 in Revere, where Massachusetts troopers were able to pursue it.

“We were told to be on the lookout and, sure enough, there it was,” Sgt. Sieberg said.

McCann quickly got off Route 1 and onto State Route 16, Sieberg said, followed by the troopers.

The chase lasted two or three minutes, until at an intersection in Everett, McCann tried to make a turn and crashed into a parked car. The cruiser went up over the curb and into a fence, according to Sieberg.

Then McCann backed the vehicle into one of the Massachusetts cruisers, he said. Unable to get away, McCann surrendered peacefully.

There were no injuries in the crash, according to Sieberg.

McCann was charged with failing to stop for a police officer, possession of a stolen motor vehicle, operating to endanger, operating without a license, assault and battery with a dangerous weapon, operating negligently, and making an unsafe lane change.