BANGOR — An Augusta man with a history of federal offenses pleaded guilty Tuesday to robbing the Bank of Maine Hallowell branch in June.

John Cecil Slater, 66, claimed during the robbery to have had a hand grenade and a gun, and demanded $15,000 in $100 bills. There was no weapon displayed in the June 23 robbery.

When police caught up with him in New Hampshire on July 7, he said he had spent most of that cash on “food, cigarettes, hotels and a 2002 motorcycle he purchased on the day he robbed the bank,” wrote the prosecutor, Assistant U.S. Attorney F. Todd Lowell, in the government’s version of the offense.

Slater most recently served 60 months in federal prison after being convicted of possession of firearm by a felon. He was released in August 2009, according to the Federal Inmate Locator website. Investigators said he was in the process of moving to Gardiner when he robbed the bank.

The note used during the robbery said, “Im Here to Rob your Bank, no silent Alarms my cell Phone rings, your all dead, I have a hand grenade, and a gun, no marked bills, or inked, if so, one day I will come back and kill all of you, do you understand.???”

On Tuesday, Slater, balding and with gray hair and a beard, sat next to his attorney, William S. Maddox, reading the documents.

Slater wore a dark blue jail uniform over a white, long-sleeve sweatshirt.

In a hoarse voice, Slater responded to a series of questions by U.S. District Court Judge John A. Woodcock Jr. during the 20-minute hearing.

“I quit school, then I got a GED and I went to college for three years,” Slater said. He said he’s been treated by a psychologist and takes medication, partly for anxiety.

Except for prescribed drugs, he told the judge, “I haven’t done any drugs or alcohol for 32 years,” he said.

On Aug. 20 he pleaded not guilty to the bank robbery charge.

He changed that plea to guilty Tuesday morning. Slater said he agrees with the government’s version of the crime.

Slater was identified through surveillance photos taken at the bank robbery and investigators classified him as “armed and dangerous” as they conducted a multistate search for him.

Lowell said he had written consent from the defendant for the forfeiture of the 2002 Yamaha motorcycle that Slater bought the day of the robbery so that was being resolved through a civil process rather than continuing as a criminal forfeiture.

Woodcock advised Slater that the conviction carries a 20-year maximum prison term, a maximum fine of $250,000, and up to three years of supervised released, as well as restitution.

The judge told Slater he would be calculating the sentence following a presentence report prepared by the federal probation office.

Slater remains in the custody of the U.S. Marshal Service pending sentencing and walked from the courtroom with his hands shackled behind his back.

After the hearing, Maddox said he had little more to add. He said he understood that Slater was suffering from diabetes as well as post-traumatic stress disorder.

Slater reportedly served in combat as a Marine in Vietnam. He also had been convicted of a series of state and federal crimes, including sex offenses, forgery and theft, among others.