Investigating Trump's Shooting, Perpetrators Leave Message 'July 13 Will Be My First '

JAKARTA - An investigative team working on the motive behind the attempted assassination of former President Donald Trump found a message posted to the Steam gaming platform which they believe was written by the suspect.

The perpetrator said "July 13 will be my first show, watch the progress," according to three law enforcement sources briefed on the investigation.

Investigators also found searches on the internet for Trump and President Joe Biden over the phone belonging to Thomas Matthew Crooks, sources familiar with the investigation told ABC News.

Crooks (20) is known to have searched for the date of Trump's rally in Butler, Pennsylvania, and the date of the Democratic National Convention in Chicago, the source said.

The suspect's cell phone was one of several devices collected by law enforcement investigators as they attempted to draw up a timeline for the assassination of the former president at a rally on Saturday last weekend.

"What is starting to emerge is a portrait of troubled young people turning to violence," said John Cohen, contributor to ABC News and former intelligence chief at the Department of Homeland Security.

Cohen, who specializes in the mass shooting phenomenon, said investigators may never determine a single or definite motive for the attack.

Sources familiar with the investigation told ABC News that the search for the suspect's phone history did not reveal indications of Crooks' political views or the motive for the shooting.

Investigators also found no digital traces of suspects showing any affiliation with international or domestic terrorist groups. They also cannot identify any ideological relationships with Trump and/or Biden, according to sources.

"Most likely the cause is a combination of mental health problems, ideological beliefs, and personal feelings of complaint, the same combination of factors that occurred in almost every school shooting and attacks that caused mass casualties over the past few years. Like those incidents, the signs of warning are there, they are not recognized," Cohen said.

"Threats are real but those around them don't understand what they witnessed or how it would happen last Saturday," he added.

The FBI on Sunday morning identified Crooks as a suspect. US Secret Service / Secret Service said snipers shot dead Crooks at the scene.

Firefighter Corey Comperatore, a father who attended the rally, was killed, and two others nearby were injured, officials said.

When investigators analyzed the suspect's phone, they looked at his search history, including questions for Trump and Biden. However, the history of the search did not necessarily reveal Crooks' political views, sources told ABC News.

Law enforcement officials investigating the assassination attempt told lawmakers on Wednesday about 20 minutes have passed as Secret Service snipers first saw Crooks on the roof and when the first shots were fired, according to law enforcement officials and lawmakers briefed on the matter.