How Do the Mentally Ill Get Their Weapons to Kill?

The news just reported the mentally ill Muslim who killed one person and wounded five in Seattle, Washington used two legally acquired semiautomatic pistols. How did Mr. Haq get these weapons as his lawyer noted his ten year severe case of bi-polar disorder?

Also authorities never explained how Mr. Lui in Arizona acquired his weapons. That gentleman randomly shot and killed two people in a suburban Phoenix Walmart parking lot last fall.

More often than killers the mentally ill are victims, their lives ended by officers unsure of how to manage the situation. Mr. Alpizar died in the Miami Airport last fall for this very reason. It is estimated that people with severe mental illness are 4 times more likely to be killed by police.

It seems critical to keep weapons out of the hands of the mentally ill for the safety of all involved. So how did Lui and Haq get their guns?