(CBS News) ALBUQUERQUE -- Jonelle Ellis' 25-year-old brother Kenneth returned from Iraq with severe post-traumatic stress disorder. He spent three months as an in-patient at a Veterans Affairs hospital.
"We can offer them all the services in the world, but we can't protect them from what's going on in their head," Jonelle Ellis says.
On Jan. 13, 2010, police investigating an auto theft ring stopped Ellis for questioning in a convenience store parking lot. He held a gun to his head, pacing for ten minutes, telling police he did not want to hurt anyone else but was going to kill himself. Police told him repeatedly to put down the gun.
Then suddenly, a police officer shot him. Ellis died at the scene.
He was one of 18 people shot and killed by Albuquerque police since 2010. Police Chief Ray Schultz says as many as 40 percent of them, like Ellis, were mentally ill.
"They are in active crisis, and very often their actions become very aggressive," Schultz says. "And officers find themselves in a situation where they have to make a split-second decision. And very often it's a life-and-death decision."
Since 2005, Schultz's department has run a program to teach officers crisis intervention techniques, using actors to portray people with mental disorders. But just one in four officers gets that training.
"Our goal is to try to limit those number of encounters," Schultz says. "What we're wanting our officers to do is get there quickly, but once they get there, slow things down and help the person work through their crisis."
Though he admits his officers need the training, Schultz insists that past police shootings are justified -- including Ellis'.
"That's a case I did review, and the officer made that decision based on the actions of Mr. Ellis," Schultz says.
Watch: Mentally ill getting prison bars instead of hospital beds, below.
He acknowledges Ellis did not point the gun in the direction of anyone else but says, "He was a threat because of his location and all the people that were there. Officers had made a decision that they were going to keep him contained in a very specific area. Once he started to make a movement away from that area, they had concerns about his ability to harm other people."
The family is suing the city over Ellis' death. The day after CBS News' interview with Schultz, the civil court judge in the case ruled police used excessive force when they shot Kenneth Ellis. Not at any time, she said, was he a threat to police -- or anyone else.
The Department of Justice is now investigating the Albuquerque Police Department's use of force. The department recently found that four other police departments -- Seattle, Portland, New Orleans and Puerto Rico -- routinely use excessive force against mentally-ill suspects.