Authorities are digging into the background of Elias Rodriguez, the suspect in the fatal shooting of two Israeli Embassy staffers.

Police said the 30-year-old from Chicago opened fire outside the Jewish Museum in Washington, D.C., Wednesday night, killing Yaron Lischinsky and Sarah Milgrim.

Rodriguez was employed by the American Osteopathic Information Association in Chicago. The organization released a statement Thursday.

"We were shocked and saddened to learn that an AOIA employee has been arrested as a suspect in this horrific crime," the statement read in part. "Both the AOIA and AOA stand ready to cooperate with the investigation in any way we can."

Scripps News tracked down archive footage appearing to show Rodriguez participating in a 2018 protest organized by the ANSWER Coalition, an activist group.

Scripps News, formerly known as Newsy, spoke with Rodriguez in Chicago during the demonstration opposing Amazon’s potential plans to build a second headquarters in the city.

“We feel like if we can keep Amazon out, that is a huge victory and demonstrates the power of people coming together — being able to say no to things like gentrification and corporate subsidies,” said Rodriguez, who identified himself as a member of ANSWER Chicago.

The Anti-Defamation League has criticized ANSWER, which has chapters nationwide, for supporting anti-Israel causes. The organization has held protests against genocide and in support of the “Free Palestine” movement. In April, it posted photos from a demonstration in Washington, D.C., on its website.

It is unclear whether Rodriguez participated in any of the group's anti-war or pro-Palestinian protests.

Investigators said Rodriguez shouted “Free, free Palestine” after Wednesday night's shooting. The FBI is also working to authenticate writings allegedly authored by him, though officials have not disclosed what those writings say.