BACHELORETTE Desiree Hartsock was touched when handsome hopeful Brooks Forester confessed he’d been abandoned by his dad as a kid, but the contestant’s father insists there was a good reason for his disappearance.

In an exclusive ENQUIRER interview, Gary Forester, 72, revealed the stunning secret why he left his family behind in Boise, Idaho, to move to Costa Rica – he was an informant for the feds!

“I love all of my children, but I moved to Costa Rica because I got a job offer,” Gary explained.

“I am a homeopathic  doctor, so I took a position down there…but  I was also an informant for the CIA and DEA. I can’t go into all of the details because a lot of that information is still secret but, needless to say, it was fascinating and also dangerous.”

On the show, Brooks, 28, a marketing rep and parttime model, emotionally told Desiree, 27, that his parents divorced when he was 13 and he had been angry with his father for years.

But “Brooks and I have a great relationship now,” insisted Gary.“The time I was gone is in the past and we are all fine now.”

Garfy – who runs a large  fruit farm in Livingston, Texas, with his current wife Zhu Xu Mei – says he doesn’t know if his son will be the last man standing on the hit ABC show’s finale in August, but he hopes so.

Although Season 9 just premiered, filming wrapped in early May, and Desiree DID choose a fiance, say sources.

“Brooks didn’t confirm to me that he and Desiree are engaged,” Gary added. “But I did tell him that if they are, she would be welcomed into the family with open arms.”