The mother of an unarmed, bipolar man shot and killed by Santa Rosa police has filed a $10 million lawsuit against the city and the officers, alleging use of excessive force.

Richard DeSantis, 30, was shot by officers responding to a 911 call from his wife, who told dispatchers he was firing a gun in their home because he thought he was hearing noises from the attic.

The lawsuit, filed in U.S. District Court by his mother, Adrianne DeSantis, is the second filed by the family since the April 9 shooting.

The suit names the city, Police Chief Ed Flint and Officers Patricia Mann, Rich Celli and Travis Menke as defendants. The city's attorney said the officers had reason to believe that DeSantis was armed and fired in defense of their lives.

A similar suit was filed in June by DeSantis' widow, Patricia. The suits are expected to be heard together, said Adrianne DeSantis' attorney, John Burris of Oakland.

Santa Rosa City Attorney Brien Farrell said police were responding to reports of gunfire in a home where DeSantis' wife and children were at the time.

"In addition to that, as they were arriving at the house, they were told he was firing it again," Farrell said.

Police said they ordered DeSantis to get down on the ground and he briefly complied, but rose and charged the officers.

Adrianne DeSantis' lawsuit says her daughter-in-law told police "in a clear and loud voice, that this was a mental health emergency and that her husband was unarmed."

A report by the Sonoma County Sheriff's Department said police fired a "low-lethal weapon" to subdue DeSantis. When he kept coming, the report said, conventional weapons were fired by the other officers. -- Kerry Benefield