HOUSTON -

Community leaders said Wednesday that they want the U.S. Attorney General's Office to investigate the death of a mentally-ill double amputee who was fatally shot by a Houston police officer.

Houston police said Officer Mathew Marin, a five-year veteran of the department, felt his partner's life was in danger when he shot Brian Claunch, 45, in the head at a group home on Polk near Sidney in southeast Houston about 1:30 a.m. Saturday.

Officers were called out to the home after Claunch became agitated when his caregiver wouldn't give him a soda and a cigarette, officials said. Claunch threatened to kill the caregiver, sources close to the investigation said.

"When officers arrived and went inside to speak with him, he was situated in a wheelchair and holding an unknown object," said Houston Police Department spokesperson Jodie Silva.

The unknown object turned out to be a pen. Investigators said Claunch, who had been diagnosed with schizophrenia and bipolar disorder, repeatedly threatened an officer in his room. Police said when Claunch refused police orders, Marin shot him.

Sources close to the investigation told KPRC Local 2 that the responding officers asked for a crisis intervention team, but one was not available.

Activists are questioning the officer's actions. They believe it was excessive force.

"What we see is here is ... another overreaction to the situation," civil rights attorney Randall Kallinen said. "It's just as fast to pull a Taser and shoot as a gun. Either one of those officers could have pulled their Taser and shocked this individual, and Brian Claunch would be alive today."

"The community should be alarmed and concerned because the next one could be one of your loved ones," said Johnny Mata of the Greater Houston Coalition for Justice.

Houston Mayor Annise Parker said she is trying to determine if HPD flags facilities officers have been called to before where there are people with known mental health issues.

Houston police records indicate that Marin also fatally shot a suspect in 2009. Investigators at the time said Marin came upon a man stabbing his neighbor to death at an apartment complex and opened fired when the suspect refused to drop the knife. According to state records, Marin has been trained in crisis intervention and mental health situations.

The Police Chief issued a statement Monday.

"The Houston Police Department places the highest value on human life and events like these are tragic and unfortunate for everyone involved."

McClelland said HPD's Homicide and Internal Affairs Division, the Harris County District Attorney's Office's Civil Rights Division and the FBI are investigating the shooting. 

Community leaders have said they want an independent police review board to investigate and hold officers accountable for their actions.

Houston police said there have been 22 officer-involved shootings so far this year, resulting in 10 suspects' deaths. There were 15 officer-involved shootings in 2011, which resulted in seven suspects' deaths.