"He had to use a hack saw to get the job done to chop up Amy Giordano," he said.
DiGirolamo, 33, was ordered to remain in jail in lieu of $1 million bond.
He was arrested last week at his parents' Brooklyn, N.Y., home after skeletal remains believed to be Giordano's were found last weekend in a remote pond in Staten Island.
Authorities believe the remains are Giordano's because pictures of her son, whom DiGirolamo fathered, were inside the suitcase, Meidt said. DNA tests are pending.
Meidt said DiGirolamo killed his mistress because he could no longer afford to support two households and that he told a longtime friend beforehand about his intentions.
Authorities said they located the remains with the help of that friend, John A. Russo Jr.
According to prosecutors, Russo knew of the killing before the fact and helped DiGirolamo buy drain cleaner, reinforced garbage bags and a saw blade to use in the killing. Meidt told the judge that Russo also waited for DiGirolamo in Staten Island to help dispose of the body on June 9.
Russo was expected to soon face his own arraignment for evidence tampering charges.
Russo's lawyer, George Vomvolakis, said Russo has known DiGirolamo since 1991 but didn't think he would actually kill anyone.
"Even when the guy bought the stuff, at no point did my client take this guy seriously," Vomvolakis said.
Then, Russo received a phone call from DiGirolamo on June 8 "saying it's done," Vomvolakis said.
Besides Russo, Meidt said police also have testimony from friends who say DiGirolamo told them about the killing.
DiGirolamo's lawyer, Jerome Ballarotto, said his client will fight the charges.
"The state's case is extremely circumstantial," Ballarotto said. "It's based on statements made by individuals whose veracity and credibility have not been tested in any way whatsoever."
Giordano was last seen alive on June 7. Two days later, her 11-month-old baby was found abandoned in the parking lot of Christiana Hospital in Newark, Del.
DiGirolamo has since admitted he left the child, even as he argues through his lawyer that he had nothing to do with Giordano's disappearance. He pleaded guilty in November to reckless endangerment and child abandonment; the child remains in foster care in Delaware.
DiGirolamo faces a term of 30 years to life in prison if convicted of the murder and evidence tampering charges against him.
Ballarotto said Friday that his client had four-hours notice last week that he was going to be arrested.
"Why sit in your parent's house, with your passport in a dresser drawer, with a four-hour head-start if you're not an innocent man?"
