HARTFORD, Conn. — False arrest and malicious prosecution allegations have been dismissed against state police officials in a lawsuit filed by a retired police sergeant who was acquitted of interfering with the investigation into a fatal car accident involving his son.

A Connecticut judge ruled last week that police officials had government immunity and some claims were not backed by sufficient evidence. A defamation allegation remains pending.

Retired Windsor Locks Sgt. Robert Koistinen sued in 2014 after he was found not guilty of interfering with the investigation into the 2010 crash involving his son, Michael Koistinen, who also was a Windsor Locks police officer.

Michael Koistinen was sentenced to five years in prison for striking and killing 15-year-old bicyclist Henry Dang while off-duty. Police said there was evidence Michael Koistinen was intoxicated.