Have you ever worried if someone that has been in you life is still alive?

I lived with this guy for around 6 months in halls in my first year at uni.
He was best friends with another flatmate (who is now my best friend). Ken is/was(?) gay and Mark was not, but they had a laugh and Ken was a great person. Anyway, Ken was prone to buying Mark more drinks than was necessary when we went out and even spent £50 on him for his birthday. (After living there for 3 months - you know where this is going) At the end of Ken's stay with us, he took Mark out for an expensive dinner which they both enjoyed and then, at the end Ken said he wanted to say a few words.
These were words to the effect of (paraphrased) "I have AIDS and I've been in love with you since the moment I saw you".

Ken moved out the very next day. I suspect he had already packed. I don't think it was the AIDS thing that bothered Mark, we both had a chat about it and neither of us had even thought about how it had affected us while we were living with Ken, we wanted to know about him. He has had a terrible time in life, mostly his family after he came out and a previous lover, the one we think passed AIDS onto him. He drank too much (even in the morning), but now we know why.

It's been around 4 years since we've even heard anything about him. We didn't know any of his other friends to ask. I really hope he's OK, he's ones of the people that never deserved what he got. He was regularly ill when he moved out, not debilitating but he was very unwell far too often for my liking.

Where is he now?