Hidden inside the Dam on the Trespasser version of Isla Sorna a skeleton can be found. The deceased starved while hiding from Velociraptors, after he'd managed to crawl into the dam losing blood. While it's still speculation to assume the skeleton and Harold Greenwood are one-in-the-same, it's generally accepted.
Starved? Where did that info came from? I would guess he bled to death. Also, we know that skeleton is Harold Greenwood.
And that's why you can't trust the JP wiki. A lot of its "information" is speculation without any source. Doesn't Anne herself suggest the contrary, that instead he died from blood loss rather than starvation?
VA144: He must have been scared. He was wounded, he crawled in here, maybe losing blood. Guess he thought it was safe.
I also find it very hard to believe his attacker (if there even was one) would have hung around long enough for him to starve - that would indicate he stayed in there for a very long time. Unless he really was so terrified that he refused to come out...
Harold probably was a spy of Biosyn who came to the island with the crashed Biosyn helicopter that can be found elsewhere on the island; although, according to some unused sound files he was a U.S. Marine.
No source on it. Also, Hammond's voiceover script says he is an adventurer. To be honest I think there would be some more info if he actually was a spy.
No source, but there is this line:
VA143: "Greenwood, Harold. USMC." Looks like it came from a novelty shop.
Just judging by what Anne says, though, he likely wasn't a US Marine at all, since she doesn't think his nametag or dogtag or whatever she is reading looks genuine.
Also, checking out the JP wiki further, they've got a .gif file of Nedry waving his finger which they claim is the one that appears in the movie, which isn't accurate at all; the one on the computer in the movie is a charicature of Elvis with Nedry's face slapped on, while the one on the wiki is a generic one you can find anywhere on the internet. Things like that are why I'd like it if we could refrain from attempting to use that wiki as a reliable source of reference in the future.
EDIT: Ah, Draco just beat me to the Voiceover thing.