What is HIAS, group alleged Pittsburgh synagogue shooter obsessed over?

The ire in many of the posts, including one from just hours before the shooting started, was aimed at a group called HIAS, the Hebrew Immigrant Aid Society.

"HIAS likes to bring invaders in that kill our people," the post read. "I can't sit by and watch my people get slaughtered. Screw your optics, I'm going in."

In another post, Bowers wrote: "You like to bring in hostile invaders to dwell among us? We appreciate the list of friends you have provided," and linked to the National Refugee Shabbat event, which was celebrated Oct. 20 at more than 300 gatherings across the U.S. and Canada.

So, what is HIAS?

The group originally formed in 1881 to help Jewish people flee pogroms in Russia and other parts of Eastern Europe and now helps persecuted refugees from all countries. 
"There are no words to express how devastated we are by the events in Pittsburgh this morning," the group said Saturday in a statement. "As we try to process this horrifying tragedy, we pray that the American Jewish community and the country can find healing."