I paid back a loan from a friend who stole from me, did I do the right thing?

A longtime friend helped me pack for moving the other day. The day before, while buying packing tape and other items, I came up short on cash, so he paid out $100.00 for the items and we agreed that I would pay him later on, before he departed for home. I'd suspected him of stealing from me in the past but could never definitively pinpoint him as the thief as other people also had access to the missing items around the same timeframe. But this time, while he was sleeping on my couch, I noticed something of mine inside his open duffel bag. A green glitter ink pen was sticking up out of the bag, and I could clearly see the glue remnants of the nametag that I'd taped to the shaft while at work just two days prior. I went over and looked into the bag and saw other items of mine inside, so I dragged it into the kitchen, went through it and pulled out numerous items belonging to me, and to the recently deceased homeowner I'd been renting a room from. I set aside my friend's items and re-packed the bag with them, which was noticeably lighter. In all, he'd pilfered over 40 items, including a Coleman coldheat soldering tool, a tomtom navigator and a pair of my sterling silver hoop earrings. When he woke up, I made up an excuse to get him to leave. He called me a day later and asked for the money, even though by now he'd noticed what'd happened. I stalled for two days, really angry about what he'd done, realizing that he'd probably taken things gone missing in the past, including my original birth certificate and immunization record. In the 11 years I've known him, he has without fail presented himself as a very good friend; helpful, respectful and caring. He always volunteers to help out with moving, cleaning or anything you need help with, he has done minor but quite competent mechanical repairs around my home and in my car, etc. He did a lot of work around my house over two days and was really a big help to me. He has given me plenty of reasons to appreciate his friendship. This is the first time I've actually caught a person in unauthorized possession of my things; even worse is the major disappointment and heartache that it turned out to be him. The only clue I'd ever had that it might be him is the proximity of time between his visits and things turning up missing. But other people also had opportunity. When things come up missing, anyone who's been in your home is suspect. Who do you blame without more information, without actual proof...if you blacklist and 86 the wrong person from your life, you irreparably damage a longtime valued friendship which might occur once or twice in a lifetime if you're lucky. Obviously this person is no longer a part of my life now that I have definitive proof. Some friends say I had no right to go through his things even if I saw my pen sticking out of his bag. I feel no remorse, I worked hard for the money to buy the stuff he tried to steal, and I also feel a responsibility to safeguard my landlord's things that his children should rightly get first dibs on. Others think I should not have paid him back the money, that he owes me restitution. He has a low-paying job but this doesn't automatically implicate him in past occurrences. Any way you want to look at it, the bottom line is, he is mentally disturbed and sociopathic. He needs professional help that I can't give him. He lent me money in good faith and I feel I should honor the debt. And I don't want to give him any reason to continue coming around! Was I wrong to pay him back, just a sucker, should I have given him the shaft, make him pay for past transgressions that I now know in my heart are probably true?