neighbor richard burg said he tried to talk to long's mother about getting her son help. >> i said, can't you get help? she said, well, he doesn't want to get help. >> reporter: police say they've had several run-ins with long. they even considered him for a 5150 which allows authorities to involuntarily hold someone they feel is a danger to themselves or others. >> in april of this year, deputies were called to his house. he was somewhat irate and acting a little irrationally. they called out our crisis intervention team, our mental health specialists, who met with him, talked to him and cleared him, didn't feel that he was qualified to be taken under 5150. >> reporter: it's unclear if police knew if he had a gun at the time. >> there are a growing number of examples around the country where law enforcement is able to step in, to assess the risk posed by an individual, and to take steps to prevent an attack. in some cases, it's providing a person access to mental health services. it could also include taking steps to prevent access to firearms. >> reporter: but even when authorities do t