New York City’s police commissioner says an internal NYPD investigation into the chokehold death of Staten Island resident Eric Garner could take “upwards of three to four months.”

Speaking on CBS’ “Face the Nation” on Sunday, Commissioner William Bratton said interviews of officers had already started. The NYPD investigation will determine if any department policies were violated.

A Staten Island grand jury last week decided not to indict Officer Daniel Pantaleo in Garner’s death, sparking nationwide protests.

A bystander’s video showed Garner saying “I can’t breathe” as officers held him down. Authorities say Garner was being arrested in July on suspicion of selling loose, untaxed cigarettes.

Bratton said the NYPD investigation would likely conclude before a federal civil rights probe that was also announced last week.

(AP)