Police raid DC shooting suspect Elias Rodriguez's Chicago apartment

Agents and officers in tactical gear, carrying rifles and at least one ballistic shield, were seen swarming the brick building around 9 a.m.

One of them also showed a sign hanging in a window reading, "Justice for Wadea."

A neighbor, John Wayne Fry, told reporters outside Thursday that the window belonged to Rodriguez. 

"That gave me the impression that they were very, very sensitive people, especially about the issue of Palestine," he said.  

Israeli Prime Minister Benjamin Netanyahu called the suspect a "brutal terrorist" Thursday and condemned liberal governments in Europe that he accused of supporting Hamas over Israel. 

It left more than 1,200 civilians dead, including at least 40 Americans, according to the Defense Department.

Seven days after the Hamas attack, Wadea's landlord Joseph Czuba, 73, stabbed him 26 times with a knife and attacked his mother, too. A jury found him guilty in February of murder, attempted murder, hate crimes and other charges.

A possible manifesto condemning Israel's response to the Hamas attack has been circulating online, attributed to Rodriguez without confirmation. Dan Bongino, deputy director of the FBI, wrote on X that the bureau was aware of the document and investigating its authenticity. 

"The subject is in custody and interviewed last night at approximately 1 a.m.," he added. "As this is a pending investigation, we will share more with you when we are able."

Metropolitan Police Chief Pamela Smith said Rodriguez is the only suspect.

The article appears to have been taken down, but an archived version shows he accused Amazon of "whitening Seattle" and claimed that the corporation forced people into "deeper and deeper poverty."

The outlet described him as a member of the "Party for Socialism and Liberation" - at least at the time. The group, which has publicly criticized Israel's response to the Oct. 7, 2023 Hamas terror attack, disavowed Rodriguez Tuesday and condemned the shooting.

"He had a brief association with one branch of the PSL that ended in 2017. We know of no contact with him in over 7 years.

The victims of Wednesday night's shooting have been identified as Sarah Milgrim, a U.S. citizen who worked at the embassy, and Yaron Lischinsky, a Christian Israeli. 

Lischinsky's father, Daniel Lischinsky, told Fox News' Trey Yingst that the two were dating, and his son had planned to propose to Milgrim soon. 

"They were in love, one for the other," he said. "The embassy told us they were like a star couple at the embassy. I never expected something like this."

They were killed walking out of an event hosted by the American Jewish Committee - that focused on finding humanitarian solutions for Palestinians in Gaza.

Fox News' Alexandra Koch and Stephen Sorace contributed to this report.