TROY – One of the men accused of the gruesome Christmas-time 2017 killings of two women and two children pleaded guilty to a murder charge under a plea deal that leaves open the slightest possibility he could someday get out of prison.

Justin Mann pleaded guilty to four counts of second-degree murder during an afternoon appearance in Rensselaer County Court on Friday. He admitted his role in the killings of Brandi Mells, 22; Shanta Myers, 36; and Myers' two children Jeremiah Myers, 11, and Shanise Myers, 5.

Mann, 25, told the judge his co-defendant, James White, 39, carried out the killings. As part of his plea, Mann will testify for the prosecution at White's upcoming trial.

Mann and White were charged with first-degree murder after the four were found in their basement apartment in Lansingburgh. Outside the door, Christmas presents had been left for the victims.

In response to questions by Chief Assistant District Attorney Matthew Hauf, Mann outlined how the killings occurred over a two-hour period between 7:40 and 9:40 p.m. Dec. 21, 2017.

Mann said they arrived from Schenectady by bus and bicycle and went to the rear basement apartment at 158 Second Ave. in Troy's Lansingburgh neighborhood. Once inside they tied up Mells, Shanta Myers and Shanise Myers. Mann said White slashed Mells to death first, followed by Shanta Myers then Shanise Myers. When Jeremiah Myers came into the apartment, he was tied up and White killed him, Mann said.

The two men left the apartment with a flat screen television, two X-boxes and the controllers, Mann said. They then rode the bikes back to a nearby bus stop to catch a bus to Albany where they transferred to another bus that took them back to Schenectady, Mann told the court.

A first-degree murder charge would have carried a maximum penalty of life in prison without the possibility of parole.

"The plea is in the best interest of my client. It gives him the outside possibility of being paroled one day," said Joseph Ahearn, the lawyer representing Mann.

"He's accepted responsibility for his own conduct within that house. It's the most horrific crime we've seen in this county in the 23 years I've been practicing. I think everyone's relieved part of its over," Ahearn said following Mann's plea.

Under the terms of his plea deal, Mann will serve four concurrent prison terms of 25 years to life.

White is headed to trial on April 29 before County Judge Debra Young. It's been estimated the trial could last up to four weeks.

As part of the agreement, Mann must testify if required by the prosecution. Young warned Mann that if he did not adhere to the agreement or committed another crime she would sentence him to a prison term of 100 years to life in prison. A sentencing date has not yet been set for Mann.

The victims were discovered when a property manager checked the apartment at 158 Second Ave. on Dec. 26, 2017 — five days after they were killed. The four victims were found bound with their throats slashed. Police who examined the scene described it as bloody and horrific.

The deal reached by the Rensselaer County District Attorney Mary Pat Donnelly and Ahearn follows Young’s Feb. 15 ruling that prevented prosecutors from showing jurors a statement Mann gave to police after the killings.

“I don’t talk,” Mann repeatedly told State Police Investigator Jason DeLuca.

DeLuca testified during a July suppression hearing that he believed that Mann, who is described as having a learning disability, meant he would not "snitch." DeLuca said he did not believe Mann was invoking his right to remain silent but Young ruled otherwise.

While Mann’s statement was tossed, prosecutors still have video evidence that allegedly shows Mann and White entering and leaving the area of the apartment and later boarding a bus to ride to Schenectady with items that police said were taken from the apartment. Other surveillance shows the men arriving in Schenectady.

Mann and White were charged with nine counts of first-degree murder, four counts of second-degree murder, one count of first-degree burglary, one count of second-degree robbery and two counts of fifth-degree criminal possession of stolen property.

Donnelly, a Democrat, inherited the quadruple homicide case from former District Attorney Joel E. Abelove, a Republican, who was personally prosecuting the case when he lost a re-election bid last year.

"Everything that we've learned about the case since taking office and even prior has gone into every decision that we've made. Obviously justice for the victims is our priority and our sole motivation," Donnelly said.

Before leaving office, Abelove met with relatives of the victim and warned them that the new DA lacked his experience and the case could suffer. The remarks were heard by other prosecutors in the office, Donnelly said. The state district attorney's association slammed Abelove for the remark.

"I've made sure to make this is not political whatsoever. This is about those victims and their families," Donnelly said. "We're in a good place. We have a good very handle on how things are going.. I feel really good on getting things started on April 29."

Donnelly said a decision has not yet been made on whether to call Mann to testify against White.