A jury has convicted former physician Martin MacNeill of drugging and drowning his wife – and now The ENQUIRER can reveal the dark secrets of the twisted “DR. DEATH.”

MacNeill, 57, thought he’d committed the perfect murder by forcing his wife Michele, a 50-year-old former beauty queen, to undergo plastic surgery, and then pretending she’d collapsed due to a medication mix-up.

But jurors believed prosecutors who claimed the scheming con man killed the mother of eight in April 2007 so he could start a new life with his 37-year-old mistress, Gypsy Willis.

While MacNeill’s trial transfixed the nation, The ENQUIRER went behind the scenes to uncover his chilling past – and here’s what we found.

The once-respected Mormon church leader was a “serial killer,” according to an ex-lover, who claimed in a legal affidavit that MacNeill tried to murder his mother when he was young “but his sister had called 911 and medical personnel were able to revive her.”

The former girlfriend also alleged MacNeill told her he’d killed his brother, Roy, in the bath because his repeated suicide attempts had become “an embar­rassment.”

MacNeill also boasted of working with Dr. Jack Kev­orkian, the “mercy killer” who assisted in more than 130 suicides, ac­cording to his daughter Alexis.

Prosecutors discovered MacNeill served time for forgery, theft and fraud after writing $35,000 in worthless checks in 1977. He also lied to get into two different medical schools and law school, and claimed to be men­tally ill to qualify for government disability!

The creep pocketed more than $100,000 in Veterans Administration and Social Security ben­efits over the years after being declared a “latent schizophrenic.” But two of his daughters claim he never exhibited such tendencies.

Accusations of rape, and complaints of unprofes­sional conduct and misdiagnosis dogged MacNeill during the 10 years he worked at the Brigham Young University health clinic. He was fired in 1999 for undisclosed reasons.

When his wife caught him looking at pornography in August 2000, MacNeill allegedly threatened to kill her and then himself with a butcher knife. Their son Damian wrestled the knife away from him, and MacNeill spent the night in a psych ward.

Damian – who tossed his mother’s medications on his father’s orders on the night she died in 2007 – committed suicide three years later.

Shortly after his wife’s death, MacNeill sent their adopted daughter, Giselle, back to Ukraine for the summer, only to abandon the 16-year-old there. Then the monster and his mistress stole Giselle’s identity to create a new identify for brunette lover Willis. MacNeill even falsified a marriage certificate for the couple, listing their wedding date as the day of his wife’s funeral.

“The father we knew…he was just a facade,” said his daughter Alexis. “We’re so happy he can’t hurt anyone else.”