Looks like a common swift (Apus Apus), apparently there are common parasites and lice that weaken them (they attach to the body) this may have been the cause? These birds do not live that long (between 4-6 years) and they are best suited for living in very warm temperature (between 32-35C).
Found a lot of interesting stuff here: http://www.commonswift.org/Veterinary-Help-for-Common-Swifts.html
Apparently if you overfeed them their stomach will be overloaded and it can lead to death.
Yes, yes I'm back.
Somewhat.
