(CNN)As officials try to put together a picture of the alleged Pittsburgh synagogue shooter, one focus of the investigation is his social media postings, the FBI said. Here's what we know so far about suspect Robert Bowers, 46:

He allegedly made anti-Semitic statements after his arrest
While in custody and receiving medical treatment, Bowers told a SWAT officer he wanted all Jews to die and also that "they (Jews) were committing genocide to his people," according to the police criminal complaint. The bloodshed took place on the same day as Saturday Shabbat services. At the time of the shooting, three different congregations were holding services at the Tree of Life.

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He blamed Jews for helping migrant caravans
On his Gab.com account, Bowers claimed Jews were helping transport members of the migrant caravans. He shared a video that another Gab.com user posted, purportedly of a Jewish refugee advocacy group HIAS on the US-Mexico border. Another post that Bowers commented on described HIAS' overall efforts as "sugar-coated evil."

Seventeen days before the attack, Bowers posted a web page from HIAS that listed a number of Shabbats that were being held on behalf of refugees, an official said. On that list was a Shabbat address that is less than a mile away from the Tree of Life Synagogue. (The chief executive officer of HIAS, Mark Hetfield, said Bowers is not known to the group.)

He called those in migrant caravans 'invaders'

According to his posts, Bowers believed that those in the migrant caravans were violent because they were attempting to leave countries that had high levels of violence. And Bowers repeatedly called them "invaders" on his Gab posts. "I have noticed a change in people saying 'illegals' that now say 'invaders'," read one post, six days before the shooting. "I like this."

A law enforcement source confirmed to CNN that investigators believe the social media postings belong to Bowers and that the language on his account matches the suspected motivation behind the shootings.

His most recent post was five minutes before police were alerted to the shooting

In that Gab post, Bowers said he "can't sit by and watch my people get slaughtered. Screw your optics, I'm going in."

His Gab account has frequent anti-Semitic postings

He has reposted a number of posts on his social media accounts that tell Jews to get out or leave. Gab is a social media platform that advocates for free speech and puts nearly no restrictions on content.

(In a statement posted online, Gab says it "unequivocally disavows and condemns all acts of terrorism and violence...Gab's mission is very simple: to defend free expression and individual liberty online for all people." Gab said it was alerted to the suspect's profile on their platform, backed up the data, suspended the account, and contacted the FBI.)

His posts included criticism of President Trump

Among the many anti-Semitic social media posts were comments suggesting that President Trump was surrounded by too many Jewish people. "Trump is surrounded by k****", "things will stay the course," read one post on the Gab social media platform, which used a derogatory term to describe Jews. Another post, apparently intended as an insult, read: "Trump is a globalist, not a nationalist," Bowers said two days before the shooting. "There is no #MAGA as long as there is a k*** infestation.