"A lot of people won't believe this because of fear, a lot of people won't believe this because they won't, don't want their little, you know, version of reality altered. But I know what I've gone through," he said. "It's like, am I crazy? I've got to be crazy, I hope I'm crazy because maybe I can get help. But every time I think that, something else happens to prove that I'm not crazy."
UFO investigator Chuck Zukowski, who has dealt with thousands of claims of UFO sightings for nearly 25 years, said Romanek represents a small minority of those who've experienced things that defy explanation.
"About 90 percent of the stuff that I see, that comes in to me can be explained. It's the 10 percent and that 10 percent means that I have to go out there physically, look at what they saw, talk to people in person and out of that 10 percent, you may get 2 or 3 percent which is a total unknown," he said.
Zukowski said he has spent countless hours conducting his own investigation of Romanek's videos and documentation and said it is clear that something physical is happening to Romanek.
An x-ray shows the presence of an implant in Romanek's leg, which he says appeared after an alien abduction. When ABC News asked for an independent medical assessment of the implant, Romanek said it suddenly disappeared.
Romanek showed "Primetime" photos of puncture marks on his legs, which he claims were the result of "alien testing" and could not have been self-inflicted.
"I'll wake up, not know anything happened, and I'll have puncture marks, and they're usually in triangles, the ones that I get, perfect triangles," he said. "I found some on my back, didn't even know I had them."
Romanek also told ABC news that his camera went missing for a few of days, and when he found it again, photos of aliens appeared mixed in with his other photos.
"I don't know how they got there, but they were there when we had downloaded pictures off our camera," he told ABC News. "To me they look real. I mean there's so much detail in them. I don't know how they got on my camera but they look like E.T.s."
Zukowski told ABC News that Romanek's story and markings are consistent that of other abductees' stories.
"A lot of things that's happened to him, including the implants and where the implants were placed are common with other abduction, [or] ... I should say scenarios," Zukowski said.
But skeptics argue that Romanek and others like him are just seeing what they want to see.
Lisa, Romanek's wife of seven years, has also become a believer. She said she is "absolutely sure" that her husband is being visited by aliens.
"I've been there and lived it with him. There's no doubt in my mind that what he is saying is real, is true," she told ABC News.
Raising their three children outside of Denver, Lisa Romanek, 40, said that for the past eight years her family has endured the unexplainable.
"A lot of things, we try very hard to look for what other reasons could explain it," she said. "But when like all your remotes in your house disappear for three days and you have searched everywhere, and then you wake up the next morning and they're all lined up on the counter, that's something I can't explain when I've searched for them."
She doesn't just blindly follow her husband's whims, she said.