NEW YORK (PIX11) – The NYPD’s civilian watchdog is investigating why officers decided not to immediately arrest Daniel Penny, the 24-year-old Marine veteran who choked Jordan Neely to death aboard the subway.

A spokeswoman for the Civilian Complaint Review Board confirmed on Friday that a complaint had been filed and an investigation into NYPD protocol is now open.

Penny was charged with second-degree manslaughter in the death of Neely, a homeless man and street performer suffering from a mental health crisis, aboard an uptown F train on May 1. Video captured Penny placing Neely in a fatal chokehold.

Penny surrendered to the NYPD and was arraigned Friday. He was walked into the courtroom shortly after noon for his arraignment on a charge of manslaughter in the second degree. He did not enter a plea. Prosecutors said they are seeking a grand jury indictment.

The judge set his bond at $100,000 and Penny was freed pending trial. He must surrender his passport within 48 hours and he cannot leave New York without prior approval.

There has been a public outcry from some, including Rev. Al Sharpton, about why Penny was questioned by the police and then released when there was a death. Protesters have also questioned the length of time – about 10 days – it took the Manhattan district attorney to bring charges.

Attorneys representing Penny have said he was acting to protect himself and other passengers when Neely began acting erratically on the subway.

It may also be legally possible for other passengers on the train who were seen on video holding down Neely to face charges. Rev. Al Sharpton is among those pushing for that accountability.

New York Attorney and Legal Analyst Andrew Lieb told PIX11 News it is unlikely the Manhattan district attorney will bring the case. However, he said it is viable under New York law.

“Just like any situation, where we have a bank robbery, the getaway driver is also liable, we call that being an accessory,” Lieb said.