The man accused of strangling his wife, and allegedly plotting to frame their 9-year-old daughter years later, demonstrated a chokehold to a fellow jail inmate several months ago, prosecutors now claim.

Jury selection in the Manhattan Supreme Court case against Rod Covlin began Monday over the grisly death of his estranged wife, Shele Danishefsky, almost a decade ago.

Their daughter discovered Danishefsky’s body in the bathtub about 7 a.m. on New Year’s Eve 2009. While an initial theory was that Danishefsky may have had an accidental fall and then drowned, signs of foul play surfaced.

Her body, which did not initially undergo an autopsy at her observant Jewish family’s wishes, was exhumed in spring 2010. The medical examiner determined that Danishefsky had died not from drowning but rather strangling, and an injury to one of her neck bones suggested that a martial arts-style chokehold was employed.

Covlin had allegedly bragged to friends that he was a black belt in Taekwondo.

Before jurors were brought into the courtroom, prosecutors said new information had just surfaced in the case.

Matthew Bogdanos told Justice Ruth Pickholz there is recent video of Covlin in the jail’s law library that “shows the defendant demonstrating a chokehold to another inmate.” The video does not have audio, and is dated about Nov. 9, Bogdanos said.

Bogdanos said while evidence showing a defendant behind bars is typically “problematic,” in Covlin’s case, “the overwhelming probative nature of this evidence clearly outweighs any potential prejudice.”

“He demonstrates a chokehold,” Bogdanos said.

The prosecutor said his office only confirmed existence of the video in January.

If introduced in court, Bogdanos said, “the Medical Examiner will view this portion of the video, in which the defendant is demonstrating a chokehold, [and] the Medical Examiner will say, ‘that action is a perfectly consistent with my findings at autopsy.’”

Should a martial-arts expert testify, he will say the man “in the video is doing is a chokehold that is being performed correctly,” Bogdanos said.

The judge has not decided on the video’s admissibility, nor the admissibility of a martial-arts expert’s testimony.

Covlin’s lawyer, Robert Gottlieb, offered a hearty laugh about the purported chokehold video.

“This clearly falls under that cardinal rule—that black letter law that we all were taught—and that is: You have got to be kidding me,” Gottlieb said, explaining he had first learned of the purported clip this morning.

Gotlieb insists there’s no proof Covlin knows how to do a chokehold. But Covlin does know that prosecutors will argue that he knew how to perform one, meaning he might well “do his own research into the absurd allegations” while awaiting trial.

Jury selection is ongoing.