A Pakistan-born South Florida man has been accused of posting detailed bomb-making instructions to online sites frequented by extremists, including supporters of ISIS, according to a federal complaint unsealed Monday.

Tayyab Tahir Ismail, 33, posted the instructions at least five times between July and September, prosecutors said. He faces up to 20 years in prison if convicted.

According to investigators, Ismail posted messages of support for ISIS and did his own online searches on how to build bombs, though there is no evidence that he actually had live explosives. He also allegedly brought ISIS propaganda publications back to the U.S. from Pakistan when he returned from a trip there last year.

"You are surrounded by methods to hit them. Kill the devil's soldiers without hesitation. Make them bleed even in their own homes," read one message Ismail is accused of sharing online. "There are plenty of methods to attack my brother."

Officials said one of Ismail's posts included step-by-step instructions on building a suicide vest. FBI specialists determined that viable explosives could be built using the techniques Ismail allegedly described.

FLASHBACK: PSYCHIATRIC HELP, THEN PRISON FOR JEWISH CENTER BOMB PLOTTER

Ismail was an acquaintance of James Medina, who was sentenced to 25 years in prison last year for plotting to bomb a synagogue and Jewish school center during Passover in 2016. The two lived together while Medina was working on his plot, which was an undercover FBI sting operation using a fake bomb.

"On the day Medina attempted to bomb the synagogue, Ismail learned of Medina's plans to move forward and conduct the attack, but he did not alert law enforcement," the affidavit said.

After Medina's arrest, Ismail surrendered several firearms at authorities' requests, court documents showed. However, he was not charged in that case.

VIDEO SHOWS ALLEGED ISIS SUPPORTER BRAGGING OF PLOT TO BOMB GAY BARS AND UC BERKELEY

The FBI said it's been aware of Ismail since October 2010, when he allegedly made terrorism threats at a Florida homeless shelter, claiming he was an "Al Qaeda soldier" and would "blow it up." He also responded to an insult from a woman by allegedly saying, "we throw women like her in the ditch."

Ismail was arrested Friday, court records showed, and a Dec. 26 bail hearing has been scheduled.

The Associated Press contributed to this report.

Click for more from WSVN.com.

