BOSTON — (CNN) The FBI and Boston police made their move on terror suspect Usaamah Rahim because a bugged phone call tipped them off that he was about to act in an alleged plot to kill police, authorities say.

Rahim, who officials believe was radicalized by ISIS and initially planned to behead a conservative blogger, was shot dead Tuesday in a parking lot; an associate, David Wright, 25, was arrested and charged with obstruction.

Authorities are now trying to determine the depth of Rahim’s network. Officers have raided locations in Massachusetts, where Rahim lived, and a Rhode Island home belonging to another of his associates.

Investigators have not revealed the results of the raids.

The third associate’s contact with Rahim — who authorities believe was radicalized by extremists — went beyond an “Internet relationship,” one law enforcement source said. Authorities have not named or arrested that person.

Officers shot Rahim two hours after he allegedly talked to Wright in a tapped phone call Tuesday, authorities have said.

Rahim planned to come out swinging with a knife to kill police officers soon — probably Tuesday, Wednesday at the latest, according to FBI agent Joseph Galietta, who listened in.

“I’m just going to, ah, go after them, those boys in blue. Cause, ah, it’s the easiest target,” Rahim told Wright, according to an affidavit from Galietta.

Rahim referred to his planned act of jihad as “going on vacation.” Wright advised him to make out a will before he left. He’d be departing soon, Rahim allegedly told Wright, with the FBI listening in.

Rahim, 26, and Wright were apparently tight — Rahim called him his nephew on Facebook, where he thanked him for attending his wedding. Both of them used aliases on Facebook. Rahim went by “Abu Sufyaan” and referred to Wright as “Dawud Sharif Abdul-Khaliq.”

Rahim had recently purchased three military fighting knives on Amazon.com. The FBI intercepted at least one delivery and X-rayed it before letting it continue on to Rahim. He was originally planning to behead someone in another state, Galietta said.

His target? Conservative blogger Pamela Geller, who had organized a Prophet Mohammed cartoon drawing contest in Garland, Texas, last month, law enforcement sources told CNN. Two men tried to shoot participants at that event, but an off-duty police officer working security shot them dead.

On CNN’s “New Day” Thursday, Geller said she was feeling “fine” despite allegedly being a target. But, she added, she now has a guard with her 24 hours a day.

“They are coming after me for violating the Sharia, for violating blasphemy laws and they mean to come after everyone,” she said.

“Drawing a cartoon, an innocuous cartoon, warrants chopping my head off? That’s too far. I just don’t understand this.”

“They’re going to come for you, too, Chris,” she told anchor Chris Cuomo. She blamed news outlets such as CNN for not airing cartoons of the Prophet Mohammed after the terror attacks on the satirical French magazine Charlie Hebdo, which is known for publishing cartoons that mock all religions, including Islam.

Employees were slain by gunmen who stormed the magazine’s Paris office in January.

Geller argued that the decision not to show the cartoons, which some Muslims find offensive, is a violation of free speech and amounts to “kowtowing” to extremists.

Geller began in publishing at the New York Daily News. After 9/11, she started blogging about Islam and spoke out more against Islam. The Southern Poverty Law Center, which tracks hate groups and speech, says Geller’s public activism took root in 2007 when she joined a group pushing to block the opening of a public Arabic-English school in Brooklyn.

In 2010, she co-founded the American Freedom Defense Initiative. The group includes subsidiary programs Stop the Islamization of America and Stop Islamization of Nations. It says it has several tenets, including freedom of speech “as opposed to Islamic prohibitions of ‘blasphemy’ and ‘slander.'”

Geller played a key role in pushing the so-called “ground zero mosque” debate. Her group planned rallies against a proposed mosque and community center — with Geller at the helm.

The FBI had been watching Rahim for a few years and said his behavior had changed in that time. He had made social media threats to police officers, they said.

On Facebook, Rahim “liked” ISIS as well as a radical cleric and a historic Islamic scholar credited with theology that helped lead to radical Islam.

Anti-terrorism authorities had Rahim under 24-hour surveillance, said Vincent B. Lisi, FBI special agent in charge.

And they had been observing Wright and the other associates as well, who they believed were radicalized.

Wright waived his Miranda rights and spoke openly with FBI agents, Galietta said in the affidavit. He, Rahim and the third person had met on a Rhode Island beach to talk about the beheading plan.

“Wright indicated that he agreed with Rahim’s plan and supported it,” the affidavit said.

But Rahim, a security guard, became impatient and needed more accessible targets.

“I can’t wait that long,” he told Wright over the phone, according to the FBI affidavit.

Two hours after the phone conversation with Wright, FBI and Boston police officers confronted Rahim in the parking lot. Their weapons were not drawn, but then things went south. Rahim pulled a military grade knife and went after them, they said. Officers drew their weapons and shot him dead.

On the phone, Wright had told Rahim that he should delete evidence data on his smartphone. “Get rid of it, before anybody gets it; make sure it’s completely destroyed.”

U.S. District Court in Boston charged Wright with obstructing a federal investigation by destroying electronic evidence on Rahim’s smartphone. A detention hearing was scheduled for June 19 after prosecutors said he was a flight risk.

Wright faces a maximum penalty of five years in prison if convicted. His attorney, Jessica Hedges, cast doubt on the legal quality of the investigation but did not specify complaints against investigators.

Following the shooting, Rahim’s brother Ibrahim Rahim posted a claim on social media that police had shot Usaamah Rahim in the back while he waited for a bus and spoke with their father over his cell phone.

Social media lit up with accusations against officers.

But Boston police said surveillance video told a different story, and community civil rights and religious leaders were invited to have a look at the video and talk to reporters about what they’d seen.

Rahim was not at a bus stop, not on the phone at the time of the shooting and was not shot in the back, the communitiy leaders said. “The information reported by others that that was the case was inaccurate,” said Darnell Williams, president and chief executive of the Urban League of Eastern Massachusetts.

Williams said prosecutors want Rahim’s family to see the video before showing it to the public.

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