Cop-killer Herman Bell slinked into his new life of freedom Saturday.

The 70-year-old former Black Liberation Army member slipped out of the Eastern Correctional Facility in Napanoch sometime before 10 a.m., avoiding media, sources said.

The ex-gang member — convicted of shooting NYPD Officers Joseph Piagentini and Waverly Jones to death in a 1971 ambush in Harlem — left in an unmarked vehicle headed to Brooklyn, sources said.

Bell, who served 40 years behind bars before being paroled over the objections of his victim’s survivors and cop unions, was initially released from Shawangunk Correctional Facility Friday. He was shuttled to the second nearby prison to throw off potential threats.

Mayor de Blasio does not welcome the ex-con back.

Bell’s “release is an affront to the finest Police Department in the world,” he told The Post.