Pastor's wife, 65, buys pistol from gun shop and shoots herself dead in the parking lot

• Police believe Harriet Deison shot herself with gun she had just purchased
• Found dead in her Lexus sedan on Saturday afternoon
• Takes 20 minutes to undergo background checks and buy a gun in Texas

Before the purchase, a customer must fill out a form with personal information, show a government-issued ID and pass a background check. The process takes around 20 minutes,