(CNN) In the search for answers after the Pittsburgh synagogue shooting , there is newfound scrutiny on the suspect's social media posts and how his anti-Semitism merged with a hatred of immigrants.

The suspect, Robert Bowers, complained about immigrant "invaders" six days before the shooting.

While there is no such invasion happening, this rhetoric has blanketed right-wing media in relation to the Central American migrant caravan that's been in the news this month.

And Bowers apparently noticed. On October 21, he wrote on Gab, "I have noticed a change in people saying 'illegals' that now say 'invaders'. I like this."

It may never be known where he heard this hateful language. But a review of television and online content shows how "invasion" and "invaders" became a talking point in October -- not just in the darkest corners of the web, but on Fox's prime time shows. The network's rivals CNN and MSNBC used "invasion" in the context of explaining the right-wing narrative.

Within days of the new caravan's formation in Honduras, Fox News hosts and Republican congressmen were using dehumanizing language and casting the migrants as an imminent threat. In reality, the nearest caravan is about 1,000 miles from the nearest US port of entry, and many of the migrants say they want to seek asylum through legal avenues.

On Fox News, the word "invasion" was used in relation to the caravan more than 60 times in October, according to closed captioning transcripts. (This includes repeats of programs.) "Invading" was brought up more than a dozen times.

On Fox Business, the word "invasion" was invoked more than 75 times in October, mostly on Lou Dobbs' program.

Fox's Tucker Carlson referenced an "invasion" as early as October 16.

Eleven days later, on October 27, minutes before entering the Tree of Life synagogue, the suspect wrote another post about "invaders" and said "I'm going in," seemingly linking his anti-immigrant attitudes to his attack on the synagogue.

One of the congregations that rents space at the synagogue, Dor Hadash, reportedly has a partnership with HIAS, the Hebrew Immigrant Aid Society, which has a long history of helping refugees.

The suspect claimed in his final post on Gab that "HIAS likes to bring in invaders that kill our people."

It is unknown how the suspect heard about HIAS. The group received only a tiny bit of national news coverage in the weeks leading up to the shooting, according to Google News search results.

But the imagined threat posed by the migrant caravan was all over the news. And President Trump tried to keep it that way, by repeatedly tweeting about and talking about the caravan. On October 18, he cast the migrant issue as a midterm election opportunity for the GOP, saying "this will be an election of Kavanaugh, the caravan, law and order and common sense."

The right-wing rhetoric was sometimes accompanied by accusations that Democrats were funding or supporting the caravan.

Social media sites were clogged with conspiracy theories along these lines, and some of the theories even parroted anti-Semitic tropes.

Billionaire George Soros was brought up by GOP stalwarts like Rep. Matt Gaetz, who tweeted a video on October 17 and said it showed someone in Honduras "giving cash 2 women & children 2 join the caravan & storm the US border @ election time. Soros? US-backed NGOs? Time to investigate the source!"

Soros is Jewish and a favorite boogeyman of the far-right -- two things that are not always a coincidence.

In the comment sections on YouTube and other sites, anonymous users frequently went even further than Fox News' TV stars.

Here's just one example from YouTube: "This is an invading army and invasive species, this assault on America must be stopped by any means necessary!"

Conservative websites also employed the term "invasion" liberally.

"This is an invasion. There's no other way to describe it," Glenn Beck wrote on his own website on October 23.

But few conservative news sources can rival Fox News' reach. The millions of viewers who tuned to its prime time programs heard guests on Fox also use words like "invaders" and "mob."

On October 19, Fox contributor Newt Gingrich said "this is an invasion. This is an act of attacking the United States' sovereignty." He became one of the loudest voices repeating the term "invasion" on TV and online.

"We have to treat this as an invasion," Rep. Steve Scalise said on Laura Ingraham's show on October 23.

"It's not a caravan, it's an invasion," Tomi Lahren said the next day on Fox.

Afternoon anchor Shep Smith, a lone Fox voice who spoke out against the rhetoric used by his colleagues, told viewers on October 23, "The president has called it an ASSAULT on the US border. It is absolutely not."

On his phone, he read a tweet from a viewer who told him, "Sorry, Shep. We are not falling for your fake story. This is an invasion."

Smith tried to tell her that Trump was preying on her fears.

Later in the day, the fear-mongering continued on Fox. Ingraham's 10 p.m. monologue was titled "leftists aiding and abetting an invasion." She referred to the migrants as "this invading horde."

In the wake of the Pittsburgh massacre, some observers have pinned the hate crime on right wing rhetoric -- and the president directly.

Writing for The Atlantic, Adam Serwer asserted that "Trump's Caravan Hysteria Led to This."

The president apparently isn't second guessing himself. On Monday, he used the word "invasion" for the first time in a tweet to describe the caravan.

"This is an invasion of our Country," he wrote, "and our Military is waiting for you!"