AMANDA PERRY HAYES seemed to have it all – good looks, a happy marriage and a brand-new baby girl.

But police say behind her girl-next-door persona, the blonde beauty is a monster. They claim she helped her husband Grant kill and cut up his ex-girlfriend, Laura Ack­erson, over a bitter custody dispute involving the former couple’s two young sons.

After murdering her, authorities say Amanda and Grant, who lived in Kinston, N.C., stuffed Laura’s dis­membered body into ice chests and transported the remains to Texas in a rented U-Haul. Once there, they tried to dissolve the body parts in muriatic acid before dumping them, piece by piece, into an alligator-infested creek.

“It’s one of the most gruesome scenes I’ve seen in 30-something years of law enforcement,” said Chief Deputy Craig Brady of the Fort Bend County (Texas) Sheriff ’s Office.

LAURA, 27, WAS LAST SEEN alive on July 13, 2011, after dropping off her sons at Grant and Amanda’s apartment. They were splitting custody, with the boys staying with their dad during the week and with Laura on weekends. But Grant, who was making a living as an artist and musician, wanted to relocate to the Virgin Islands with new bride Amanda, their month-old daughter Lillian, and his sons – and Laura was stand­ing in his way.

On July 18, Laura’s partner at their marketing and graphics arts firm reported her missing. Two days later, authorities locat­ed Laura’s abandoned car at an apartment complex and followed a trail of evidence to Texas, where they found what was left of her body. Laura’s father, Rodger Ackerson of Lowell, Mich., remembers when he first learned about his daughter’s death.

“I got a call from a detective in North Carolina…He said, ‘Are you sitting down?’ ” Rodger recalled. “He said, ‘Your daughter has been murdered and we’ve found her re­mains.’”

Police indicated that parts of Laura’s body had been retrieved from Oyster Creek, near the home of Amanda’s sister in Richmond, Texas. Although the sister has not been implicated in the crime, po­lice recovered a machete – which they believe was used, along with a power saw, to dismember Laura – at her home. Grant and Amanda were arrested on July 25, 2011. He was convicted of murder at his trial last year and is cur­rently serving life in prison.

Amanda’s trial has just gotten un­derway in Raleigh – and her lawyers have indicated they may call Grant as a witness in her defense. Attorney Johnny Gaskins contends that Amanda was a “victim” who was forced by her husband to participate in the gruesome murder and cover-up.

According to the attorney, Grant told Amanda, who faces life in prison if convicted: “If you don’t do it then none of us are getting out of here alive.”