Middlesex District Attorney Gerry Leone's office ruled that 68-year-old Stamps' death was an accident and not a crime. Leone's office said Duncan's rifle fired when he tripped and fell inside Stamps' home at 26 Fountain St. The SWAT team was serving a search warrant at the time.

Authorities said Stamps' stepson, Joseph Bushfan, whom police arrested, and another man were the targets of the raid. Suso said the district attorney's report is key to the police internal investigation.

The review should be complete in two to four weeks, he said.

Selectmen did not comment on the matter, but behind closed doors last night they discussed a potential lawsuit Stamps' family may bring. An attorney for the family last week called the district attorney's explanation of Stamps' death implausible and said he will conduct his own investigation.