BUTTE, Mont. -

John Grubbs, 72, is accused of murdering another resident at the Continental Gardens.

NBC Montana dug deeper and uncovered Grubbs had a previous arrest for assault with a weapon. That charge was dismissed after he lived up to certain standards imposed by the court in what's known as a deferred prosecution.

Now retirement center administrators are wondering if they should do background checks on every resident once a year.

A Butte-Silver Bow County attorney tells NBC Montana the 2011 assault with a weapon charge against John Grubbs was dismissed because of lack of evidence and the victim had no injuries. That's one reason the charge may have not shown up on a background check.

Even if Grubbs had been living at Continental Gardens when he was charged, Human Resources Executive Director Elissa Mitchell said she wouldn't have evicted him.

"We couldn't refuse a person a rental at Continental Gardens if they were accused of something but then proven innocent, or in his case the charges were dropped," said Mitchell.

Mitchell said Grubbs could stay at Continental Gardens as long as he followed the policies. But his arrest in 2011, and last week for murder has her thinking twice.

Mitchell is looking at educating and training Continental Gardens residents to look for odd behavior in other residents.

"As far as staff is concerned, we're going to do some training there and were going to raise their awareness, what to be watchful of things to watch for," Mitchell said.

It's likely one staff member was on duty the night of the murder. Witnesses say Grubbs and the victim, Jerry Diltz, had been drinking and got into a fight about 2 in the morning over money.

Mitchell tells us she is considering annual background checks on tenants, to find out about any kind of criminal behavior.

"We're going to do the best we can to make sure an incident like this never happens again," said Mitchell.