A woman's body and that of an unidentified man were found in a home in Weare, N.H., where Maher had registered a business in the past three weeks. The New Hampshire Attorney General's Office, which is investigating the incident, said it appears the man killed her and then himself.
Maher's brother, Rick Maher, confirmed it was his sister who was killed. Maher's Facebook page has been filled with condolences since the Sunday shooting.
The New Hampshire Union Leader reported late Monday that Maher was killed by Jacob Geiser, the 19-year-old son of Maher's boyfriend, Joe Geiser.
Maher's mother, Marge Maher, said police had told her Jacob Geiser killed her daughter in the home she shared with the Geisers, the Union Leader reported. Police have not released the name of the gunman.
In New Hampshire, the Weare Police Department responded to a 911 call at 1724 River Road around 6:30 a.m. Sunday.
Police discovered a man and woman dead in the home. An investigation is under way.
The man appears to have been involved in a home invasion about 90 minutes before the two bodies were discovered, according to the New Hampshire Attorney General's Office.
Autopsies were scheduled for Monday.
Maher, 41, was the mother of four children. Her last Facebook post on Saturday said she was heading out for a bike ride.
Maher's revelation last year about her relationship with Garn was one of Utah's most stunning political scandals and led to the fall of one of the state's leading political figures.
She came forward in the waning days of the 2010 legislative session, contacting House leaders and reporters, claiming Garn, who was her boss in 1985, had bought her alcohol and hot-tubbed nude with her.
Garn denied any physical contact with the girl, although Maher insisted there was, but would not elaborate.
In 2002, she had confronted Garn and threatened to go public with the incident, and Garn, who at the time was running for U.S. Congress, later paid her $150,000 on the condition she sign a nondisclosure agreement.
Aware that The Tribune was going to report the incident, Garn took the floor on the last night of the 2010 legislative session and offered a tearful admission of parts of the episode excluding their nudity and apologized.
He received an almost-unanimous standing ovation from his colleagues, a display that was met with disgust by many.
Then-House Speaker Dave Clark, R-Santa Clara, who arranged the apology, later lost the speaker's race, and the handling of the Garn incident was cited as one of the factors.
Garn did not return a message left at his office Monday.
After her 1985 encounter with Garn, Maher's life unraveled, which she attributed to the incident. In 1986, she was driving drunk down Ogden Canyon and crashed the car, killing her friend.
She has struggled with pills and alcohol and mental health issues.
She has been embroiled in a bitter, long-running child custody battle with her ex-husband over the last several years.
The Concord Monitor in New Hamphire reported that in March her ex-husband issued an Amber Alert when Maher did not return their three children and Maher served three weeks in jail.
Then in April, the state Supreme Court reversed a domestic violence protective order filed against Maher by her ex-husband.