The man who was shot and killed by terrorism investigators had been spreading propaganda for the Islamic State group online, the chairman of the House Homeland Security Committee said Wednesday.

Rep. Michael McCaul, a Texas Republican, opened a congressional hearing on terrorism with a reference to the shooting of Usaama Rahim on Tuesday.

Rahim was shot by members of the Joint Terrorism Task Force after police say he lunged at them with a knife when they approached him to question him outside a Boston pharmacy. Boston police and FBI officials say Rahim had been under 24-hour surveillance after they received some “terrorist-related information.”

A law enforcement official with knowledge of the investigation told The Associated Press that Rahim had been making threats against law enforcement. The official was not authorized to release details of the investigation and spoke on the condition of anonymity.

McCaul said the terrorism task force was investigating Rahim because he had been “communicating with and spreading ISIS propaganda online.” ISIS is an older term for the Islamic State group.

“These cases are a reminder of the dangers posed by individuals radicalized through social media,” McCaul said.

Boston police and the FBI said Rahim was shot after he went after officers with a large military-style knife and refused to drop the weapon.

Rahim’s brother, a well-known imam, has disputed the police account of the shooting. He said his brother was shot as he waited for a bus to take him to work.

“He was confronted by three Boston Police officers and subsequently shot in the back three times,” Ibrahim Rahim wrote on his Facebook page. “He was on his cellphone with my dear father during the confrontation needing a witness.”

Ibrahim Rahim couldn’t be reached for more comment. In an email, he said he was traveling to Boston to bury his brother.

Usaama Rahim was shot outside a CVS in Boston’s Roslindale neighborhood. A spokeswoman said Rahim had worked for CVS since March.

Police said they have video showing that officers did not have their weapons drawn when they approached Rahim and that they backed up when he initially lunged at them with the knife. Police planned to show the video to civil rights leaders and clergy Wednesday during a meeting at police headquarters.

Boston Police Commissioner William Evans said Rahim had been under 24-hour surveillance by terrorism investigators.

The FBI arrested an Everett man Tuesday in connection with the Rahim investigation. David Wright, 26, is scheduled to appear in federal court in Boston on Wednesday afternoon. The charges against him have not yet been disclosed.

Authorities also searched a home in Warwick, Rhode Island, but would not confirm that was linked to the Boston shooting.

Evans said authorities had been watching Rahim “for quite a time,” but “a level of alarm” prompted them to try to question him Tuesday.

He said authorities knew Rahim “had some extremism as far as his views.”

The Suffolk district attorney’s office and the FBI said they will investigate Rahim’s shooting, a routine procedure for shootings involving police.

The Council of American-Islamic Relations will monitor the investigation, spokesman Ibrahim Hooper said.

Boston voter registration records for Rahim list him as a student. Records indicate that as recently as two years ago he was licensed as a security officer in Miami, but they don’t specify in what capacity.

Yusufi Vali, executive director of the Islamic Society of Boston Cultural Center, said the center’s security firm hired Rahim as a security guard for a month in mid-2013. Vali said Rahim did not regularly pray at the center and did not volunteer there or serve in any leadership positions.

Vincent Lisi, special agent in charge of the Boston FBI office, said authorities “don’t think there’s any concern for public safety out there right now.”

(AP)