A Boston police officer who was fired after military-grade explosives were found at his house has to be rehired — and given more than a year’s worth of back pay — according to a Civil Service Commission ruling.

Officer Kirk Merricks was fired in January 2017 after an internal investigation stemming from a 2013 arrest. Merricks’ ex-wife called police to their Plymouth home after reportedly finding grenades, blasting caps and four “explosive sticks” marked TNT in a shed outside.

Merricks was charged with 11 counts of possession of an explosive device and four counts of receiving stolen property, but pleaded not guilty and eventually saw the charges dropped in 2014. But based on an internal investigation into the explosives — and a restraining order filed against Merricks after he kicked in a bathroom door during a domestic argument — Boston Police Department officials fired him for untruthfulness, conduct unbecoming an officer and failing to obey the law.

Civil Service Commissioner Cynthia Ittleman said BPD had cause to discipline Merricks for domestic violence, but “a case involving a single, less egregious incident of domestic violence unaccompanied by other proved misconduct” did not justify termination, and said Merricks should be suspended for 10 days.

Additionally, Ittleman said BPD was not justified in firing Merricks over the explosives, noting that Plymouth police said they did not have “direct” or “overwhelming” evidence tying them to Merricks and that BPD “essentially relied on the unverified, contested statements of a witness the (department) never met,” referring to the ex-wife — who also did not testify after Merrick was indicted. Prosecutors eventually dropped the case.

Brian Decker, Merrick’s attorney, said the ruling vindicated his client.

“It’s extremely satisfying the commission ruled in our favor and he’s going back to work,” Decker said. “The charges were based simply on a claim by an ex-wife at the height of a bitter divorce. … The charges were dropped, it was unnecessary, we believe, for the department to take the actions it did.”

In 2016, Merricks had a base salary of $88,758.54, according to the Boston Herald’s payroll database.

BPD has 30 days to appeal the decision, and a BPD spokesman said the department was reviewing the decision.