An ICE agent whose house in Vermont was raided over firearms has retired as investigators continue to study the case, the Burlington Free Press reports.

Special Agent Richard Bernholz stepped down from his federal job Friday, about 13 months after ATF seized more than 155 firearms from his home in Franklin County, according to the Free Press.

Federal authorities have declined to comment on the investigation, which appears to have been sparked by a gun that Bernholz used in a shooting in Massachusetts, the Free Press reported.

Since October 2010, the longtime federal agent had been assigned to the Homeland Security Investigations Division of ICE.