Nancy Gonzalez hopes to get back baby she had with cop killer Ronell Wilson

A lawyer for Nancy Gonzalez, the one-time prison guard from Long Island who conceived a child in jail with death-row inmate Ronell Wilson, said Monday that she is undergoing mental health and substance abuse treatment in hopes of regaining custody of their baby.

The comments from defense lawyer Anthony Ricco, flanked by Gonzalez, followed a decision by U.S. District Judge Brian Cogan to postpone her scheduled Brooklyn federal court sentencing to figure out whether she'll need to register as a federal sex offender.

"There appears to be a strong argument for federal registration," Cogan said.

Gonzalez wasn't warned that having sex with a prisoner might require registration before she pleaded guilty last year. Cogan said he needed to discuss it with her before accepting the plea, and wanted more time and information before sentencing.

Prosecutors want Gonzalez to serve 10 to 16 months in prison for having sex in 2012 with Wilson while he was at a federal lockup in Brooklyn awaiting a death penalty hearing on the 2003 murder of two NYPD undercover detectives in Staten Island.

Defense lawyers have asked Cogan to give her no jail time, arguing that her crime was the product of extended childhood sexual abuse and resulting problems with drugs, alcohol and depression.

A Suffolk County Family Court judge ruled last year that Gonzalez, 29, of Huntington Station, must at least temporarily give up custody of the child, named Justus, due to neglect and substance abuse. She has another Family Court hearing in May, Ricco said.

"The decision itself was painful," he told reporters. "But she has come to see the wisdom of the court's ruling and she is doing everything under the sun to get back with her child . . . It's difficult to take care of a child when you're dealing with your own problems."

A jury last year ruled that Wilson should get the death penalty.