LOS ANGELES (AP) — A Southern California man was convicted Wednesday of blowing up his ex-girlfriend’s spa business with a package bomb in 2018, killing her and seriously injuring two clients.

A federal jury in Los Angeles convicted Stephen Beal of four felonies including use of a weapon of mass destruction resulting in death, according to a statement from the U.S. attorney's office.

Beal could face at least 30 years and up to life in prison when he's sentenced in November.

He was retried after a mistrial was declared last year when the jury deadlocked.

Beal, 64, of Long Beach, was charged with killing Ildiko Krajnyak on May 15, 2018, with a homemade bomb in a cardboard box that he slipped into her Aliso Viejo spa, about 50 miles south of Los Angeles.

Krajnyak, 48, was killed in the fiery blast when she opened the box. Two clients — a mother and daughter — she had just treated were knocked off their feet.

The blast destroyed the business and tore a large hunk from the building. Body parts were found in the parking lot.

Beal, a partner in the salon business, was jealous Krajnyak had been dating someone else after their 18-month relationship ended, prosecutors said.

“Mr. Beal was a jilted lover who wanted to obliterate his ex-girlfriend after she sought to end their relationship,” U.S. Attorney Martin Estrada told journalists at a news conference after the verdict. “He used his expertise in building rockets and explosives to create a bomb that he disguised as a mail package.”

While Krajnyak was in Hungary visiting family, Beal left the bomb at the spa for her to open when she returned, according to the U.S. attorney's office statement.

A day after the explosion, investigators searched Beal's home and found more than 130 pounds (59 kilograms) of explosive mixtures and precursor chemicals, the statement said.

“Beal had years of experience building high-powered model rockets and homemade pyrotechnics," according to the statement. “Laboratory testing determined that the explosive mixture Beal used in the bomb came from the same chemicals he had at his home.”

Beal also was found guilty of malicious destruction of a building resulting in death, use of a destructive device during and in relation to a crime of violence, and possession of an unregistered destructive device.