Thomas Matthew Crooks' parents contacted law enforcement Saturday hours before he opened fire on former President Trump at a Pennsylvania campaign rally, a source told Fox News. 

The aspiring assassin's mother and father told local police that Crooks was missing and that they were concerned about his welfare, the source said.

It remained unclear if they knew that he was in possession of an AR-15 rifle that belonged to his father.

Police have not said what actions they took after being contacted.

NEW PHOTO SHOWS TRUMP SHOOTER'S CELLPHONE, TRANSMITTER FOUND NEAR HIS BODY

An unidentified man answers the door at the home of 20-year-old Thomas Matthew Crooks, named by the FBI as the "subject involved" in the attempted assassination of former President Donald Trump, in Bethel Park, Pennsylvania, U.S. July 15, 2024.  (REUTERS/Aaron Josefczyk)

Crooks' parents are cooperating with FBI investigators as the agency tries to specify a motive for the shooting that injured Trump and killed rally attendee Corey Comperatore.

Officials completed a vetting of Crooks' phone and social media accounts, but have yet to publicize the results of that probe.

The shooter's parents, Matthew and Mary Crooks, were both licensed as professional counselors in Pennsylvania, according to state records.

They both received their social work licenses in 2002 and renewed them as recently as last year.

ERIC TRUMP ‘PISSED OFF’ FOR SECRET SERVICE AGENTS IN LINE OF FIRE, DEMANDS ANSWERS 

File photo of Thomas Matthew Crooks graduating from Bethel Park High School in 2022. Crooks is alleged to be the shooter in the assassination attempt on former President Donald Trump in Butler, Pennsylvania on Saturday, July 13, 2024.  (Obtained by Fox News Digital)

Crooks, a 2022 Bethel Park High School graduate, was shot dead by Secret Service snipers after opening fire at the rally in Butler.

The high school loner was a registered Republican but donated to a progressive campaign in 2021.

Along with his father, a registered Libertarian, Crooks was a member of a local gun club.

His mother was a registered Democrat.

NEIGHBOR SAYS TRUMP SHOOTER'S FAMILY HAD NO POLITICAL SIGNS IN YARD AS PARENTS' AFFILIATIONS SURFACE

Republican presidential candidate former President Donald Trump is moved from the stage at a campaign rally, Saturday, July 13, 2024, in Butler, Pa.  (AP Photo/Evan Vucci)

The would-be assassin earned an associate degree in engineering science from Allegheny County Community College just two months before the shooting. 

ABC News reported that he had planned to attend Robert Morris University in the fall, and had also been accepted to the University of Pittsburgh but opted not to attend.

Republican presidential candidate and former U.S. President Donald Trump reacts as multiple shots rang out during a campaign rally at the Butler Farm Show in Butler, Pennsylvania, U.S., July 13, 2024. (REUTERS/Brendan McDermid)

CLICK HERE TO GET THE FOX NEWS APP

Crooks served as a dietary aide at a local nursing home and had asked to have Saturday off because he had "something to do," according to CNN.