33-year-old Alex Crow, a landscaper from Medford, entered a Burlington Co. Courtroom to plead guilty to DeMartin's murder.
DeMartin, of Evesham, was a clothing store executive who was missing for 2 and 1/2 years before her body was found and identified last winter.
"That was so hard when he came into that room, it really was," said Marianne's mother Mary Ann DeMartin. "To think what he had done to her."
Crow, who worked on the groundscrew at DeMartin's Sagemore Drive condo complex, admitted entering through a sliding door. When DeMartin awoke to find him rifling through her purse, he says they struggled and he strangled her.
"She stopped fighting and stopped breathing," Crow said in court.
Crow drove Marianne DeMartin's car to upstate Pennsylvania and dumped her body. He then came back to NJ and left the vehicle next to a dumpster behind a convenience store in Vorhees.
Under the plea approved by the family Crow will get a 40 year sentence and must serve at least 34 years before being eligible for parole.
"We don't have to go through a trial, and it can be done and over with," said DeMartin's sister Debbie Gore. "We can try and go forward."
The DeMartin's parents say, they're sorry New Jersey doesn't have a death penalty. They say they offered the plea to him so they can get the process over with before they were gone.
Formal sentencing for Crow is set for January 9th, 2009.