State police say a former Old Lyme man who committed four bank robberies in 2007 was back at it again this year, committing at least three more.

Kenneth Buckingham, 50, was arrested on Thursday and charged in connection with a March 1 robbery at the Liberty Bank branch in Haddam, another on April 16 at the TD Bank branch in Durham, and a third on May 20 at the First Niagara Bank in Westbrook. State police said they anticipate he also will be charged in connection with the Jan. 17 robbery at Chelsea Groton Bank in Salem.

Buckingham's former career as a bank robber was ended on May 16, 2007, by police who waited in a stakeout at an East Lyme bank, anticipating Buckingham's next move.

He was charged in a spree of robberies in the towns of Salem, Centerbrook and East Lyme. While in prison, Buckingham was called to the witness stand as a jailhouse informant in two different murder trials. In 2010, he testified for state prosecutors in New London in the trial of George M. Leniart. Leniart was later convicted in the rape and murder of 15-year-old April Dawn Pennington of Montville, who disappeared in 1996. Buckingham testified that Leniart had admitted to the killing while in prison.

Buckingham also testified in the murder trial of Richard Read in New Britain, which also led to a conviction.

He admitted he was hoping for leniency in his own case, though he was never promised anything.

Buckingham was sentenced in 2011 to 75 months in prison with 13 years of special parole. He had by that time served the bulk of his sentence. Court records show his sentence was modified and reduced by four months in May 2012. His release date was not immediately available.

State police, in a written statement, said they served three warrants Thursday as Buckingham was appearing in Middletown Superior Court.

During an investigation into the string of robberies, police said, they executed several search-and-seizure warrants at hotel rooms and vehicles. State police major crime detectives worked in conjunction with state police at Troop F in Westbrook, the probation department, the FBI and various local departments.

Buckingham remains held in lieu of a total of $450,000 in bonds. He faces three counts each of first-degree robbery, third-degree larceny and second-degree threatening.

g.smith@theday.com