Dan Serafini, a former pitcher and first-round pick of the Minnesota Twins, was convicted on Monday in the 2021 execution-style shootings of his wealthy in-laws at their home at Lake Tahoe.
On the third day of deliberations in the high-profile case, a jury in Placer County, Calif., convicted Mr. Serafini, 51, of first-degree murder in the killing of his father-in-law, Gary Spohr, 70, and attempted murder of his mother-in-law, Wendy Wood, who survived being shot in the head. She died by suicide in 2023 at age 70, according to her family.
Mr. Serafini, who has denied being involved in the shootings, was also found guilty of special circumstance allegations of lying in wait and first-degree burglary.
He faces a maximum sentence of life in prison without parole. Sentencing is scheduled for Aug. 18.
During his six-week trial in Superior Court in Auburn, Calif., prosecutors described Mr. Serafini as having had an acrimonious relationship with his in-laws, who were worth millions, and said that he had once been overheard offering $20,000 to have them killed.
The prosecutors presented testimony from Samantha Scott, the family’s former nanny, with whom they said that Mr. Serafini was having an affair and who helped commit the crime. Ms. Scott, who was initially charged with murder and attempted murder, pleaded guilty in February to being an accessory to a felony and is awaiting sentencing.
Jurors also viewed security camera footage from June 5, 2021, the day of the shootings. The recordings showed a masked and hooded man, who prosecutors said was Mr. Serafini, waiting for his in-laws, who were out boating, to return to their home. Both of the victims were shot in the head at close range, execution style, the authorities said.
Rick Miller, the assistant chief deputy district attorney for Placer County, said during his closing arguments that there was a “mountain” of corroborating evidence connecting Mr. Serafini to the shootings.
“You know why he did it,” Mr. Miller said. “You know he did it. You know his motive. You know his opportunity.”
Mr. Serafini’s lawyer, David Dratman, did not immediately respond on Tuesday to a request for comment about the verdict.
In his closing arguments, Mr. Dratman had argued that an analysis by an F.B.I. expert had determined that the person on the surveillance video was 6 feet 2 inches tall, accounting for shoes and hood, which he said was shorter than Mr. Serafini’s height as measured by investigators.
“There is no way a 6-foot-3-inch man is the person on the video,” Mr. Dratman said.
