A scene in the movie The Departed:
Billy (to Trooper Brown, with a gun to Colin's head): Look, he's Costello's rat, all right? I got boxes of tapes! Evidence! Other documents proving it!
Trooper Brown (has his gun trained on Billy): Maybe you do. But right now I need you to drop the weapon!
Billy: I have evidence cold-linking this prick (referring to Colin) to Costello, all right?
Context: Billy is an undercover state trooper working with crime boss Costello. Colin is a mole inside the state police force working for Costello. Costello has just been killed by Colin prior to this scene of a confrontation between Billy, Colin, and Brown.
It doesn't appear to be idiomatic or commonly used at all--Google and Google Books have literally nothing relevant to "cold-linking". It seems "linking" would do the job. Is "cold-linking" a wordplay on something else? Or is it police slang?