ALBANY - Imagine a murderer being eligible for parole after three years in prison.

That's what Denise O'Donnell, New York's deputy secretary for public safety, said Friday could happen under what she calls a dangerous loophole in a sentencing law.

Under current New York law, a defendant convicted of murder while on parole for a previous killing could get credit for time served for the first crime.

That means a person who served 22 years for murder could be eligible for parole after three years in prison on the later murder, despite getting a new sentence of 25 years to life.

Closing the loophole is on Tuesday's agenda as part of an extraordinary session of the Legislature. Gov. David Paterson has proposed a bill that would prevent the most dangerous criminals, called A-I felony offenders, and those who commit a second child sexual assault from getting the break.

The measure would also require an offender to serve at least half his or her sentence before a medical-based parole can be granted.

Now, such a parole based on grave illness could be granted immediately after sentencing for murderers.

The Democratic majorities in the Assembly and Senate are working with Paterson on the proposal, but there is no agreement yet.

The Legislature wouldn't be required to vote on the bill on Tuesday.

“We have every reason to believe they will support this,” O'Donnell said.

Washington County prosecutor Kathleen Hogan said the loophole also hurts murder victims' families, who would have to face the emotional pain of attending biannual parole hearings years sooner because of the provision.

“It makes absolutely no sense,” Hogan said. “It is devastating to victims' families.”

Backing the bill is Janice Grieshaber Geddes, a victims' advocate.

Thursday marked 12 years since the murder of her daughter, 22-year-old Jenna Grieshaber, by a felon on parole.

“When I hear of errors or omissions in legislation that may allow someone who commits an egregious crime to be out on the streets, it nauseates me,” she said.