Did you see "Munich"?
No. But they useually do not leave footprints.
It’s not 1974 anymore. That was 36 years ago. Pre CCTV, cell phone, computer name searches, pre 9/11 al Qaeda watch lists. Co-operation by security services world wide has never been better, faster. All travel records, customs is near nigh instantaneous.
Everyone, everywhere in the modern world leaves an immense track. You might as well be traveling with an elephant. Further, those individuals will have credit, and other records, years deep, but false.
Also, If you, say, have an ID, but no record, that is like a magnesium flair for the database software.
You do something in a swank hotel in a small one capital state, that brings attention, the police are there, armed in minutes or less.
This isn’t an era of cracking off a bunch of .22’s in some youth hostel in Goatbutt hill town in Norway a generation and a half ago.