Poor GJ. I can empathise with you over this dilemma. We had 3 cats who have all sadly passed on now (from old age) but we'd kept 2 kittens from a litter of a stray we'd taken in.

The last one alive was named Esky and he was a really loving cat. Our next door neighbours did the same as your's are doing, and eventually locked him in their house so he couldn't get out.

It took a long time and many threats before we eventually got him back, and I don't know what we'd have done had the police not gone to their door. Thinking we'd called them, they opened their back door, and our cat ran home to us.

We did keep him inside ourselves after that, and he got to rather like the extra attention he was getting.

Good luck GJ. I hope you get Murphy back soon, and I hope his abcess is all better after the antibiotics you gave him.