A second defendant has pleaded guilty in the fatal stabbing of Kyle Sheets aboard his father’s boat in Mystic in Sept. 2008.

Vincent Green, 19, accepted a plea agreement this morning in which he will be sentenced to 25 years in prison for felony murder. Green and Christopher Allen, 24, boarded the Crucible on the dock at Seaport Marine on Sept. 26, 2008 with the intention of robbing Sheets, 29, of money and drugs, according to prosecutor Lawrence J. Tytla. A struggle ensued, and Allen stabbed Sheets multiple times.

Allen pleaded guilty in December and is scheduled to be sentenced on Thursday to 32 years in prison.

Green, who was 17 when the crime occurred, stood with his mother and attorney Bruce A. McIntyre this afternoon to enter his plea before Judge Susan B. Handy. He pleaded guilty under the Alford Doctrine, which means he doesn’t agree with the state’s allegations but does not want to risk conviction and the possibility of a lengthier sentence, at trial.

Sheets’ father, who was aboard the boat with his son that day, watched the pleading from the audience and is expected to be heard at the sentencings.

The state will next try to resolve the cases of Bryan Sutton and Bruce Grisafe, who allegedly served as lookouts during the botched robbery attempt.