NYPD Launches Internal Affairs Probe Into Eric Garner Choke Hold Officer

— -- The New York City Police Department has launched an internal investigation into the choke hold death of Eric Garner at the hands of a police officer, one day after a grand jury announced that they would not be indicting the officer on criminal charges.

The officer involved in the controversial incident, Daniel Pantaleo, may now be interviewed by internal affairs officers, but the other officers who were on the scene may come first as they are scheduled to be interviewed on Friday, police sources told ABC News today.

If the internal affairs investigators recommend a punishment, a department judge will be the one to decide if it is enacted.

The NYPD investigation is the second process that Pantaleo is going through, and he is also the subject of a federal civil rights investigation and can expect a civil wrongful death lawsuit from Garner's relatives.

"This is not the end of the story -- only the end of a chapter," New York City Mayor Bill de Blasio said in a statement released this morning.

A Staten Island judge approved the release of some information pertaining to the secret grand jury who decided not to indict Pantaleo with any criminal charges relating to the death of Eric Garner, a 43-year-old man who was allegedly selling loose cigarettes at the time of the July 17 incident.

The jury met over nine weeks, hearing from 50 witnesses that included 22 civilians and the rest were police officers or emergency medical responders.

The jurors saw 60 other exhibits, including videos, photos and records.

Both Attorney General Eric Holder and U.S. Attorney for the Southern District of New York Loretta Lynch, who is also President Obama's nominee to succeed Holder, spoke out on Wednesday, confirmed that they had informed Garner's widow of the federal civil rights investigation.

"Our prosecutors will conduct an independent, thorough, fair and expeditious investigation," Holder said Wednesday.

NYPD Commissioner Bill Bratton confirmed that the department trial and investigation into Pantaleo's actions will begin soon.

Former Police Commissioner Ray Kelly, who is now a contributor to ABC News, said the burden of proof is far lower in an internal investigation where a "preponderance of evidence" must be supplied to support a finding against an officer, whereas grand jury decisions are based on probable cause.

Though he estimated that an internal decision could be handed down in about six months, Kelly said it was "very difficult to say because normally they have a calendar for these things but because of the public scrutiny, they're going to move it up."

The department trial will definitely not begin this week, however, because both sides -- Garner's family's attorneys and Pantaleo's attorneys -- have been focusing on the grand jury investigation up until now, Kelly said.

"They need time to prepare their case," Kelly said.

The final avenue of potential punishment, which may end up taking the longest, is the civil trial that would come when the Garner family files a wrongful death lawsuit. Garner's relatives and their attorney have already taken the first step in the process -- which in New York City involves notifying the NYPD that they intend to sue, in this case for $75 million.

For the time being, 29-year-old Pantaleo has been suspended with pay and had both his gun and badge taken away pending the internal investigation. He has maintained his innocence and put out a statement after the grand jury decision was announced Wednesday.

"I became a police officer to help people and to protect those who can’t protect themselves," Pantaleo said. "It is never my intention to harm anyone and I feel very bad about the death of Mr. Garner. My family and I include him and his family in our prayers and I hope that they will accept my personal condolences for their loss."

Pantaleo's suspension, and the apology he offered in a statement Wednesday after the grand jury decision was announced, was not enough for Garner's widow. When asked if she would accept his apology, Esaw Garner said: "Hell no!"

"He's still working, he's still getting a paycheck, he's still feeding his kids, and my husband is six feet under," she said.

ABC News' Aaron Katersky contributed to this report.