A state representative and his former campaign treasurer each paid fines to the Commonwealth to resolve a case in which they violated campaign finance law by having a government employee serve as treasurer of a political committee.

First-term Representative Mark Cusack of Braintree paid $750, while his former treasurer, Christopher Griffin, paid $200 to resolve the case, according to letters sent by Michael J. Sullivan, director of the state Office of Campaign and Political Finance.

Copies of the letters were forwarded to the Massachusetts Republican Party after it filed a complaint with the state when the Globe reported in May that Griffin - assistant to Braintree Mayor Joseph Sullivan - appeared to have violated the law by working for Cusack, a Democrat.

State law expressly prohibits a government employee from serving as a campaign treasurer, since their job could lead them to both solicit or receive political donations.

“Based upon our review, we have concluded that after Mr. Griffin became a public employee and continued to serve as your treasurer, your committee did not comply with Section 13” of a chapter in the Massachusetts General Laws, Sullivan wrote in a July 26 letter to Cusack.

“Because your committee has made payment to the Commonwealth and appointed a new treasurer that specializes in campaign finance law, this office has determined that further action is not required and considers this matter closed,” Sullivan added.

He used much the same language in a similar letter to Griffin.