Officers shot and killed Rahim when he allegedly refused to drop his knife.
Rahim had been under surveillance by the the Joint Terrorism Task Force, and their investigation into his plans came to a head on Tuesday when they had indications that he was planning to carry out an attack on police officers. Authorities confronted Rahim in Boston and fatally shot him when he allegedly approached the officers wielding a knife.
Authorities had tapped Rahim's phone and recorded his conversations, and in the 10 days leading up to the shooting, they had him under 24-hour surveillance, according to CNN.
Officials learned recently that Rahim had purchased multiple military fighting knives, according to an affidavit by an FBI agent filed in federal court. He also discussed with another suspect his plans to behead an unnamed person (later confirmed to be Geller) outside of Massachusetts, as well as the plan to attack police officers.
During one of the tapped conversations, Rahim said he had plans to "go after" the "boys in blue," a reference to police officers, according to the affidavit.
On Tuesday, when investigators heard Rahim on the phone plotting to behead police officers, they decided to approach the suspect about the phone call, according to the affidavit. An FBI agent and a police officer then confronted Rahim outside a CVS in the Roslindale neighborhood, according to the New York Times.
When the officials identified themselves, Rahim allegedly pulled out a knife, and when they asked Rahim to drop his weapon, he responded, "you drop yours," according to the affidavit. Rahim moved toward the officers wielding one of the knives he had purchased recently and was subsequently shot by the officers, according to the affidavit.
Two other suspects allegedly conspired with Rahim as he plotted his attacks.
While two other suspects allegedly knew about Rahim's plots, details have been revealed about only one of those suspects.
Rahim called David Wright on Tuesday to tell him about his plan to attack police officers, and at the end of the call, Wright told Rahim to destroy his smartphone and wipe his computer, according to the FBI affidavit.
Wright, identified by news reports as Rahim's nephew, was arrested on Tuesday and charged with conspiring with Rahim to destroy evidence related to Rahim's plots.
The FBI said that a third person in Rhode Island was involved in the plot as well, but authorities did not identify the third suspect or detail exactly how he was involved, according to the New York Times.
Was Rahim influenced by the Islamic State?
Officials have indicated that Rahim and the other suspects involved were influenced in some way by the Islamic State or another terrorist group, but it's not clear yet what role the Islamic State played in the plots.
While discussing his plots, Rahim said he was "going on vacation," likely a reference to jihad, according to the FBI affidavit. And federal authorities said that the men were influenced by militant Islam and that Rahim had become radicalized, according to the New York Times.
Rahim liked the Facebook page for the Islamic State of Iraq in 2012, but otherwise did not mention radical Islam on social media, according to CNN. However, Rep. Michael McCaul (R-TX), chairman of the House Homeland Security Committee, said that Rahim was "communicating with and spreading ISIS propaganda online."
And the Islamic State encouraged at least one of the suspects involved in plotting the attacks, but likely did not help with specifics of the plan, U.S. officials told CNN.
While authorities seem sure that Rahim was radicalized in some way, interviews with friends and neighbors of Rahim painted conflicting pictures of his faith.
Yahya Abdullah Rivero, a member of the same Mosque Rahim attended while he lived in Miami, told the New York Times that Rahim followed radical Muslim clerics online and believed that some conservative sects of Islam were "too lenient."
However, Imam Abdullah Faaruuq, a leader at the Mosque For The Praising Of Allah in Boston, said he had known Rahim since Rahim was five years old and assured that "his family is a good family," according to NPR.
Police are downplaying how serious a threat Rahim posed to anti-Islam activist Pamela Geller.
While Rahim allegedly discussed possibly beheading anti-Islam activist Pamela Geller, law enforcement officials have indicated that he may not have advanced into actual planning for such an attack. Geller's group American Freedom Defense Initiative organized the Muhammad cartoon contest in Garland, Texas, that itself came under armed attack in May.
Boston Police Commissioner William Evans confirmed on Thursday that Rahim mentioned Geller, but said the plot was "wishful thinking." And law enforcement officials described Rahim's plan to attack Geller to NBC as a "fantasy."
Authorities considered his alleged plot to attack police officers more serious and credible.
Though it's not clear whether Rahim would have attacked Geller, she came out swinging on Wednesday when she learned of Rahim's plans.
"They targeted me for violating Sharia blasphemy laws. They mean to kill everyone who doesn't do their bidding and abide by their law voluntarily," she told CNN. "This is a showdown for American freedom. Will we stand against this savagery or bow down to them and silence ourselves?"
Rahim's family has tempered some of its initial concerns about his shooting.
Following Rahim's death on Tuesday, members of his family questioned whether his actions warranted officers firing shots.
Rahim's brother, Ibrahim Rahim, initially claimed on Facebook that officers shot his brother in the back.
Police then let Muslim leaders in Boston view the surveillance video of the shooting, after which leaders concluded that Rahim was not shot in the back. However, Imam Abdullah Faaruuq, a leader at the Mosque for the Praising of the Lord, said that the surveillance tape of the incident was "inconclusive." He claimed he could not tell whether Rahim was wielding a knife.
Boston Police Commissioner William Evans said it was clear that the officers were backing away from Rahim and asking him to drop his weapon before firing shots.
Boston police later showed surveillance footage of the incident to Rahim's family, prompting Ibrahim Rahim to admit to CNN that he was wrong.
Though it seems clear that Rahim was not shot in the back, Rahim's family on Thursday called for a thorough investigation into the shooting and moments leading up to Rahim's death.