Blackjack. A Cross Novel

TO:  UNIT 3 ChicagoFROM: DIRECTORIMPORTANCE: Critical SUBJECT:  Specimen Retrieval TARGET: Shadowy hunter-killer teams, ID'ed via signature kills worldwide. Identifiable only by skull-spine removal from victims. No witnesses, no forensics, no particular race targeted. On rare occasions, scraps of what appear to be playing cards found at murder sites. OBJECTIVE: Locate and capture any member of such teams.
MUST be taken alive for study and observation. AUTHORIZATION APPROVED FOR USE OF OUTSIDE CONTRACTOR: Individual ID'ed only as "Cross" and his team. A pure mercenary outfit, well known throughout criminal underworld--no inside informants available. Ruthless, undeterred by risk, rumored never to fail, but UNDER NO CIRCUMSTANCES to be trusted. No known political or social objective, but has proven treacherous when retained by government in the past. UPDATE: Cross and his team claim to have identified a pattern to the signature-kills, and believe they can predict a forthcoming strike. They are prepared to personally confront-and-capture, but financial arrangement alone not sufficient.
What you describe as a "Get Out of Jail Free" card is hereby APPROVED.