A 25-year-old man who held up a Norwich convenience store at gunpoint last year, then told the clerks to “Have a nice day” as he left with $400 in cash was sentenced to 12 years in prison last week despite his pleas for leniency.

Harold Montgomery of New London had completed a 4 1/2 year prison stint for a 2005 robbery spree and was on probation when he was charged with entering the GMS Mart on North Main Street on July 9, 2011, with a loaded .22-caliber pistol and demanding money.  He pleaded guilty in the midst of a probation violation hearing in July.

“The position we found ourselves in about one quarter of the way through the proceeding was not good, and my client realized it (the hearing) should end,” said his attorney, Mark S. Solak.

But at his sentencing Friday, Montgomery attempted to convince Judge Patrick J. Clifford that police had violated his rights when they stopped him on Sandy Lane a short time after the robbery. Montgomery said he was in the wrong place at the wrong time and that he had been attending school and trying to move out of state upon his release from prison. Montgomery said 12 years is a long time to spend in prison.

“I’ll be 35, and everybody else will be living and I’m still going to be in the same spot,” Montgomery said.

Prosecutor Paul J. Narducci asked the judge to impose the agreed sentence of 12 years in prison followed by five years of special parole, saying it was warranted under the circumstances.

Judge Clifford imposed the full prison term, telling Montgomery that sentencing is not about what is good for the defendant.

“You can’t be on probation and commit the same crime, with a weapon that could kill someone,” Clifford said. “My sentence has a warehousing effect to protect society.”

In 2006, Montgomery was sentenced to 4 1/2 years prison after pleading guilty to four robberies. The state said Montgomery held up a man behind Ernie’s Cafe in New London in August 2005. The month before, he drew a gun on the clerk at the Wine Merchant Liquor Store on Broad Street and demanded money. A week after that, he held up the 7-Eleven convenience store on the same street. The next week, he robbed the Exxon station across the street.