Texas Lady Bought Gun and Committed Suicide in the Parking Lot

The Dallas News reports

Harriet Deison, 65, of Dallas was found dead in her Lexus sedan near McClelland Gun Shop. Witnesses told police they heard two shots and saw smoke coming out of the car around 2:15 p.m. 
Police think Deison shot herself with the pistol she had just purchased. The Dallas County medical examiner’s office has ruled the death a suicide.
ATF spokesman Andrew Young said that in all such situations, the ATF reviews the shop’s procedures and the application the customer completed before the purchase. He estimated that the application process and background check take about 20 minutes.
Before buying a gun at a store, a customer must fill out a form with personal information, show a government-issued ID and pass a background check based on a national directory called the National Instant Criminal Background Check System.
“At that point, if the background check is passed, they buy a gun and walk out with a gun,” Young said. There is no waiting period in Texas, he said.
Young said the ATF discourages gun dealers from selling a firearm if a customer seems “under duress,” intoxicated or mentally unstable. “We recommend during the application process if there’s anything that seems wrong or illogical, don’t do the sale. It’s not worth the small amount of profit.”

What gun control law would have prevented this, the gun-rights folks often ask. Well, obviously a waiting period before collecting the newly bought gun very well might have prevented this tragedy. That's number 4 on the list of proper gun control laws.  Also, if the law did a bit more than "DISCOURAGE gun dealers from selling a firearm if a customer seems “under duress,” intoxicated or mentally unstable," this incident might have been avoided. I don't believe a person who is five minutes away from blowing their brains out appears normal.
What's your opinion?  Please leave a comment.