Boston Terror Suspect Shot by Cop Told Nephew He Was After 'Boys in Blue'

A phone exchange between Boston terror suspect Usaama Rahim and his nephew reveal that the terror suspect said he was going to "go after the boys in blue" because they were the "easiest target," according to court documents unsealed today.

Rahim was recently shot and killed by a Boston cop after he "came at the officers" with a "military-style knife" on Tuesday a little after 7 a.m. in the parking lot of a CVS in Roslindale, Massachusetts, police said.

Two hours before the incident, the FBI was listening in to Rahim's phone conversation with a 24-year-old man named David Wright, according to a court affidavit obtained by ABC News.

"Yeah, I'm going to be on vacation right here in Massachusetts," Rahim told Wright on the phone, according to the affidavit. "I'm just going to ah go after them, those boys in blue. Cause, ah, it's the easiest target."

Rahim had been under 24/7 surveillance by the FBI's Joint Terrorism Task Force, the affidavit said, adding that Rahim had recently purchased three knives on Amazon, including the weapon he allegedly used on Tuesday.

After Wright found out Rahim's whole plan, he allegedly told Rahim to destroy his phone and "completely wipe out everything" on his computer, the affidavit added.

Police said Wright was arrested Tuesday and charged with obstruction of the investigation. Police added he had also allegedly expressed an interest in taking up the ISIS call to attack police.

Wright was arraigned in federal court today, but it's unclear whether he entered a plea. His next hearing is scheduled for June 19 at 2 p.m., according to court records.

The case has touched a nerve in Boston and late this afternoon, the U.S .Attorney in Massachusetts, Carmen Ortiz, hosted a conference call with Boston-area Muslim leaders in which she urged them to report any instances of backlash because of the Rahim case.