An 81-year-old Garden Grove man was convicted Wednesday of first-degree murder and attempted murder in connection with the 2018 stabbing death of his 11-year-old stepdaughter and a violent attack on his wife at their Blossom Avenue home.

Tanh Thien Tran was found guilty on April 1 after jurors deliberated and reached their verdict around 2 p.m. The verdicts were formally read in court the following morning. Tran is scheduled to be sentenced May 28 and faces up to 37 years to life in prison.

On the morning of August 29, 2018, Tran attacked his then-36-year-old wife, San Nguyen, with a BB gun and a knife as she was preparing to leave for work, prosecutors said. The night before, Nguyen had told Tran she was looking for a room to rent for him because she no longer wanted her children living with him.

Deputy District Attorney Devin Campbell told jurors that Tran confronted Nguyen with a BB gun that looked like a real handgun, fired a shot at her arm, then dragged her into a bedroom closet and repeatedly stabbed her. Neighbors heard her screaming, “Help me, he’s killing me,” and called police.

Tran’s stepdaughter, Anh Duong, came to her mother’s aid. Tran pulled the girl into the closet and continued his attack. Nguyen managed to escape, but when she looked back at her daughter, the child appeared lifeless. She got no response when she called out to her.

Officers arrived to find Tran outside the home making superficial cuts to himself with a knife, initially keeping them back. Three children, including Anh and two siblings ages 6 and 3, were still inside. Officers eventually forced entry, rescued the children, and attempted to revive Anh. She was transported to a hospital, where she was pronounced dead.

Before losing consciousness, Anh told first responders: “My dad tried to kill me.” Those were her last words, according to prosecutors.

Campbell said Tran had grown suspicious that his wife was being unfaithful, pointing to messages on her phone. In the weeks before the attack, Tran’s search history showed he had looked up how to install GPS tracking devices on a car. His searches later turned darker — how to buy a gun, and whether a BB gun could be lethal.

After Nguyen was released from the hospital and returned home, she found a journal her daughter had been keeping that contained allegations Tran had been molesting her. Prosecutors also said Tran’s phone contained searches for pornographic videos of minors.

Defense attorney Eugene Sung of the Orange County Public Defender’s Office noted that Tran, who was 69 at the time, had met Nguyen while traveling in Vietnam, where their relationship became romantic.

Tran’s sentencing is set for May 28 in Orange County Superior Court.