Just a hunch, bit I think he/she is linked to the previous killings of the early 2000's and has been in prison for some more minor crime, he is pent up and has recently been released and has several years of frustration he needs to let go of!!
Alternatively he has no link to the other crimes and has recently been dumped/used etc and is out for revenge, once a killer has killed the fear goes and it becomes a game...the publicity will fire him on, maybe that is what the police hope and that he will slip up.
I would say that if the girls of Ipswich go quiet that he will not hesitate to move to another town. He has the taste for it now....Barmaid stay safe & do NOT take any risks, along with your pals!!!!