A serial bank robber who helped the state convict George M. Leniart of kidnapping, raping and killing a Montville girl has accepted a plea offer that involves a 75-month prison sentence and 13 years of special parole.

Kenneth Buckingham, 47, of Old Lyme, pleaded guilty Monday to four bank robberies he committed in the spring of 2007 in Centerbrook, Salem and East Lyme and to two cases involving stolen checks. Buckingham entered each bank, implied he had a gun and fled with thousands of dollars, according to prosecutor Paul J. Narducci. Buckingham, who is represented by attorney Jeremiah Donovan, had faced up to 90 years in prison for his crimes. He will be sentenced on Feb. 24.

Earlier this year, Buckingham testified for the state at Leniart's murder trial. He said he and Leniart, a repeat sex offender from Montville, had been housed together at the Corrigan Correctional Institution when Leniart admitted killing April Dawn Pennington. Pennnington was 15 when she disappeared from her parents' Montville home in 1996. A New London jury convicted Leniart of capital felony and murder in March despite the fact that the girl's body was never found, and Leniart is serving a sentence of life in prison without the possibility of release.

Buckingham had also testified at the murder trial of Richard Read in New Britain, where the prosecutor said his testimony, which also pertained to a jailhouse confession, helped secure a conviction.

Another key witness in the Leniart case, Patrick J. "PJ" Allain, had his 10-year sentence for second-degree assault reduced by four years in September. He had been convicted in an unrelated case of having consensual sex with an underage girl. Allain had testified at the Leniart trial that he and Leniart picked up April Pennington and raped her on the night that April disappeared. Allain said April was still in Leniart's truck when Leniart dropped him off that night, and that Leniart told him the next day that he had strangled April and disposed of her body.

- Karen Florin