Pastor Rick Warren says his 27-year-old son used an unregistered gun, which he purchased online, to commit suicide last week.
Matthew Warren committed suicide April 5 in his Mission Viejo home.
Police are attempting to identify the seller of the gun. Orange County Sheriff spokesman Jim Amormino said the serial number had been scratched off, making it impossible to trace.
"We can't tell if it's registered or not because the serial number is scratched off," he said. "At one point in time, it may have been, but it's going to be impossible to find out."
It is a federal offense to deface a firearmâ€™s serial number. In California, legal purchase of a gun requires a background check, and the gun must be registered.
Warren did not delve into the gun law debate, rather he has been writing about grief and forgiveness. He followed up his tweet yesterday with a reading from Matthew 6:15. â€ś'If you forgive men when they sin against you, your Heavenly Father will forgive you. But if you don't...â€™ Matt.6:14-15,â€ť he wrote.
In an email Saturday night, Warren and his wife Kay said there son struggled with severe depression and suicidal thoughts. The couple set up a mental health fund in Matthewâ€™s name.
Warren is the evangelical senior pastor and founder of Saddleback Church in Lake Forest, Calif. He became a New York Times Bestselling author when his book â€śThe Purpose Driven Lifeâ€ť sold over 30 million copies.