HOUSTON -

The man convicted of killing a Houston postal worker in 1984 has been released from prison after serving less than half of a 75 year sentence. David Isador Port was released Thursday and sent to live at the Southern Corrections Austin Transition Center in Del Valle.

Local 2 Investigates has learned Port is under Super Intensive Parole Supervision. Texas prison officials said Port will be monitored via GPS 24 hours a day and he will have a curfew. Port is prohibited from entering Harris County without permission from prison officials. Port is also prohibited from having contact with members of Debora Sue Schatz' family.

Port was convicted of killing Schatz in June 1984.

"He took something precious away from me, he did," Barbara Schatz said during an interview with Local 2 Investigates in January 2013.

Before she died this year, Schatz said she spent nearly three decades dreading the day her daughter's killer would be released.

"I would like to blow him off this earth, that's what I'd like to do," Schatz said.

Court records read Debra Schatz, 23, disappeared while delivering mail in west Houston. The 23-year-old letter carrier's car was later found abandoned on a southwest Houston street. Bloodhounds led police to a nearby house and eventually Port was arrested. Court records show Port confessed to kidnapping Schatz and then shooting her when she tried to run away. Schatz's body was eventually found in Cypress Creek off Highway 290.

"There's not a day that goes by that my wife, Debra's sister, doesn't shed a tear for her," said Schatz's brother-in-law, Phillip Harmon.

The case drew such intense media attention Port's trial had to be moved out of Harris County. In 1985, Port was convicted and sentenced to 75 years in prison. However, state records show, after serving less than half of his sentence, Port is scheduled to be released from prison Thursday.

"The stark reality is one of Houston's most insidious, cold-blooded murderers is going to be statutorily released," said Victims Rights Advocate Andy Kahan.

Port was not granted parole. The state is legally obligated to release him because he was sentenced under a now-defunct Texas law that was intended to alleviate prison overcrowding. Violent offenders convicted between 1977 and 1987 were allowed to shorten the time they are required to spend in prison by accruing so-called "good time."

Texas abolished this law in 1995, but the U.S. Supreme court ruled the change in the law could not be retroactive. Current sentencing laws now require criminals convicted of violent first-degree felony offenses to serve at least half of their sentences before being eligible for parole.

While Port's release can't be stopped, Kahan is fighting to see Port serve parole under sex offender conditions.

"That's really the only way for the community to know where Port is residing," said Kahan.

In August the Texas Board of Pardons and Paroles adopted a policy that does allow for the board to "review and consider sex offender conditions as a special condition for (those released) who have not been convicted of a sex offense and are currently on parole or mandatory release supervision for an offense which contains a sexual element."

Kahan argues evidence shows Port was trying to rape Schatz when he kidnapped her and dragged into his home.

"Her pants were unzipped, her clothing was torn off," said Kahan. "Debra tried to flee and that's when he turned around and shot her several times and killed her."

State prison officials said Port will be evaluated to determine if he should also be placed under sex offender registration and restrictions.