19 year old cat died.

My 19 yo childhood cat died this morning and my parents, who aren't the sort of people to spend money on vets (sorry, but they're ex-farmers!) and can't really afford it anyway, are wondering about the cause of death. He had been showing signs of old age for a couple of years now - general loss of muscle condition, more frequent stomach upsets. I also suspect he may have had a melanoma when I saw him a few months ago. He was found yesterday morning with a nosebleed and over the next 24 hours gradually lost all motor function starting from meowing and swallowing to eventually lifting his head etc. He had apparently been off his food in the last couple of days and, I've just found out, may have been losing his sight over the past year or so.
My gut feeling is possible anuerysm (spot the human nurse!), but my parents are wondering whether it was poisoning and are thinking about which neighbour could have done it. The bit that I can't figure out whether it's common in cats or not is the nosebleed, as different information sites say it's a cause of different things. Would be nice to be able to give them an answer before they bring out the pitchforks!