Waltham Mayor Jeanette McCarthy on Wednesday said that the city will investigate allegations of sexual abuse by an Arlington Catholic High School dean while working in Waltham in connection with a recent lawsuit.

First, the mayor said, Waltham officials must review the lawsuit documents, which they have not yet been served.

“It will be investigated fully,” McCarthy said.

Once the investigation is complete, she added, “certain decisions will be made.”

McCarthy spoke to reporters immediately following Wednesday's School Committee meeting at Waltham High School. The matter was not raised during the meeting.

Also, McCarthy told reporters, she had “no knowledge” of whether the allegations will affect whether former Waltham High School Principal John Graceffa, a defendant in the lawsuit, will still take the School Committee seat he was elected to in November. She said she has not talked to other committee members about the matter.

Graceffa, who is the dean of students at Arlington Catholic High School, attended at least a portion of last night’s meeting but a Patch editor could not to locate him during the meeting for comment.

In a lawsuit, Graceffa is accused of failing to act on prior reports of a teacher sexually assaulting students, which the suit claims led to abuse of the alleged victim. The City of Waltham is also named as a defendant.