As residents in Lewiston and across Maine express shock and despair following Wednesday night's mass shootings at a bowling alley and a restaurant, questions are being asked about one of the laws meant signed years earlier to prevent such incidents. Barely four years before a gunman’s deadly rampage, a law was signed that aimed at preventing a mass shooting like the one Wednesday night that claimed at least 18 lives.The "yellow flag" law allows law enforcement to detain someone they suspect is mentally ill and poses a threat to themselves or others.The law differs from red flag laws in that it requires police first to get a medical practitioner to evaluate the person and find them to be a threat before police can petition a judge to order the person’s firearms to be seized.As authorities searched for shooting suspect Robert Card, 40, of Bowdoin, details about his recent behavior emerged. Card underwent a mental health evaluation in mid-July after he began acting erratically while with his reserve regiment, a U.S. official told The Associated Press.A bulletin sent to police across the country after the attack said Card had been committed to a mental health facility for two weeks this past summer after “hearing voices and threats to shoot up” a military base."I don't know whether there was a report to trigger the yellow flag law," Maine U.S. Senator Susan Collins, a Republican, said."It certainly seems that on the basis of the facts that we have, that the yellow flag should have been triggered," Collins said."If, in fact, the suspect was hospitalized for two weeks for mental illness, that should have triggered the yellow flag law and he should have been separated from his weapons. I'm sure, after the fact, that's going to be looked at very closely."The limited details released by police don’t make it clear whether the yellow flag law should have stopped the suspect in the Lewiston shootings or where he got any guns he used.It’s also not clear whether the suspect’s commitment to a mental health facility triggered a federal restriction against possessing guns.Since the 1960s, federal law and most states have prohibited people from possessing guns if they have been formally committed to a mental health facility, said Lindsay Nichols, policy director at the Giffords Law Center to Prevent Gun Violence.Not everyone who stays at a facility is considered formally committed, though. Formal commitment is a court process that’s usually required to keep someone at a facility longer than about 14 days, she said.Information from the Associated Press was used in this report.