Not having ties to terrorists does not mean any person is mentally stable, as this case proves.
There have been several cases out here where the 'Legal Authorities" determined that a person was not a danger to themselves or others and that person went on to kill someone.
The mentally ill or depressed, addicts and vets are treated the same, told to just buck up and help yourself. In some Scandinavian countries they make it work by moving the problem person into normal society and folks actually try to fit in. We are probably too racist for that to work.
I will bet the police will be dumped on by a national audience, so is it time to rethink this??