This is why their boss always sent the girls out of town immediately after each job.  They'd be away while the murder was on the front pages; by they time they got back, something else was the lead news story.

Also, these crimes are all taking places in different cities, so there's very little to connect the killings.

Plus, if a henchwoman gets suspicious, she'd go to see J.P., the boss ... and that henchwoman would conveniently disappear.  Paul goes through a lot of partners.