The missing beau of singer Olivia Newton-John (search) was a deadbeat dad mired in bankruptcy and a nasty battle with his ex-wife, who dragged him into court as recently as April to force him to cough up more child support, records show.

L.A.-based cameraman Patrick Kim McDermott (search), 48, was forced to file for bankruptcy in 2000 amid heavy credit-card debt involving everyone from Home Depot to American Express, according to documents reviewed by The Post.

At the time, he claimed his biggest asset was a 1995 Toyota4Runner worth $4,500.

Meanwhile, McDermott had been paying $800 a month to support his 15-year-old son from a previous marriage to B-list actress Yvette Nipar (search).

But the financially challenged McDermott apparently slipped behind on his child-support payments, prompting a court hearing this past spring that ended with authorities transferring collection of the owed money to a special county enforcement agency.

It was only the latest salvo in his ongoing bitter war with Nipar, who once accused him of encouraging their son to play hooky.

McDermott has been dating the famed Aussie singer Newton-John for the past nine years. He mysteriously vanished during a fishing trip July 1.

He was last seen eating aboard the chartered boat "Freedom" about four miles from port in San Pedro Harbor in L.A.

His wallet, tackle box and fishing rod were found on board. His car was discovered still in the marina parking lot.

Authorities said they haven't ruled out anything in the disappearance, including that he may have accidentally drowned or faked his death.

The handsome, gray-maned McDermott was first reported missing by his ex-wife.

Nipar — a former soap star who also appeared in the short-lived "Robocop" TV series — told authorities she was concerned after he failed to appear at a family gathering on July 6.

A Coast Guard spokesman Tuesday denied reports that witnesses saw McDermott leave the boat when it reached shore.