A federal affidavit released Wednesday afternoon provided the first detailed glimpse at the terrorism investigation that sparked a fatal Roslindale confrontation between law enforcement officials and Usaama Rahim.
The document was filed in support of a complaint against David Wright, who allegedly advised Rahim as he plotted to behead someone in another state, then shifted the focus of his aggression to police officers here.
The core of the case against Wright is the accusation that he told Rahim to destroy his cellphone “with intent to impede, obstruct, or influence” an investigation.
But in the course of laying out those allegations against Wright, the document goes into detail about why federal officials said they had Rahim on 24-hour surveillance in the first place.
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Below is some of the key information laid out in the affidavit.
Ordering knives
Police and federal agents have said Rahim approached them with a knife before they opened fire and shot him three times. In an affidavit, authorities said they tracked his purchase of three knives, though they do not say which one they believe he used in the confrontation.
Rahim allegedly spoke to Wright about the purchase of one of the knives, an Ontario Spec Plus Marine Raider Bowie fighting knife that authorities say “is 15 inches long when opened, contains a 9.75” blade, and weighs 22.4 ounces.”
In a conversation relayed by authorities, Rahim allegedly told Wright that it was a “nice little tool” that was “good for carving.” He also made reference to “carving wood and like, you know, carving sculptures . . . and you know,” authorities said.
Rahim bought the three weapons during two visits to Amazon.com, according to the affidavit, which describes them as “fighting knives.”
Rahim purchased two Ontario Spec Plus Marine Raider Bowie knives, and one Ontario Knife SP6 Spec Plus Fighting Knife, according to investigators handling the case.
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Both knives are made by the Ontario Knife Company — or OKC — a New York-based manufacturer of sporting and kitchen knives.
The SP6 retails at $43.99 on Amazon’s website. It’s described as a 13-inch knife — including the blade and handle — made of carbon steel and “Kraton,” a rubber-like material that’s used for creating the grips on weapons.
Buyers on Amazon who claimed they have purchased and used the SP6 described the weapon as “one of the best knives available, especially for the price.”
One buyer who wrote a review about the knife on Amazon said it was great for fighting.
“I would not recommend this blade for anything else other than self defense and stabbing,” the review said.
The Ontario Spec Plus Marine Raider Bowie knife, which Rahim bought two of in separate transactions, retail for $55 on Amazon’s website, and are also made of carbon steel, according to a description of the product.
Shifting the plan
On May 31, Wright and Rahim allegedly met with another person on a Rhode Island beach, where they discussed beheading a victim in another state.
But by June 2, authorities say, Rahim had changed his mind. The affidavit laid out the following conversation, which it claims took place at 5 a.m. Tuesday, two hours before Rahim was shot to death.
RAHIM: And, ah, but I can’t wait that long, I can’t wait that long man.
***
WRIGHT: Are you, are you trying to figure out where, are you trying to go to [the other state]?
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RAHIM: No.
WRIGHT: You are not, I’m trying to understand, wait, you are not trying to go to [the other state]?
RAHIM: No.
***
WRIGHT: Oh, oh wait a minute, oh ah, you are going to be, ah, you’re attempting to go on vacation I see.
RAHIM: Yeah, I’m going to be on vacation right here in Massachusetts…I’m just going to ah go after them, those boys in blue. Cause, ah, it’s the easiest target and, ah, the most common is the easiest for me…
Destroying the phone
During the same conversation, the affidavit says Wright advised Rahim to cover his tracks in the exchange below.
WRIGHT: [m]ake sure also, very important, make sure that, ah, at the moment that you decide to that you ah, delete, you delete ah, from your phone or you break it apart. Throw it down to the ground.
RAHIM: Yup.
WRIGHT: Get rid of it, before anybody gets it; make sure it’s completely destroyed.
RAHIM: I will.
WRIGHT: Because, at the scene, at the scene ,CSI will be looking for that particular thing and so dump it, get rid of that. At the time you are going to do it, before you reach your destination you get rid of it.
Andy Rosen can be reached at andrew.rosen@globe.com. Follow him on Twitter at @andyrosen.
Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.