Liberal polices are "reversing" gains made in fighting crime in New York City, former NYPD Commissioner Bernard Kerik said Saturday.

Appearing on "Fox & Friends: Weekend" with host Ed Henry, Kerik blamed Mayor Bill DeBlasio and the City Council for a recent spike in violent crime. Murder investigations in 2019 spiked to 9.4 percent this year.

"I don't blame the NYPD. I blame the mayor. I blame the City Council. I blame the people that promote this anti-cop rhetoric," Kerik said. "They took stop-question-and-frisk away from the cops. They took enforcement out of law enforcement."

SUSPECT, 13, IN MURDER OF BARNARD COLLEGE STUDENT TESSA MAJORS ORDERED HELD WITHOUT BAIL

On Friday, a 13-year-old boy was arrested by the NYPD in the shocking stabbing death of 18-year-old Barnard College student Tessa Majors. The boy later testified in court that he had handed a knife to his friend, who then stabbed Majors so brutally he saw “feathers come out of her jacket."

The teen, who is not being identified by Fox News, was ordered held without bail by Family Court Judge Karen Lupuloff. He is charged with second-degree murder, first- and second-degree robbery and criminal possession of a weapon.

Kerik believes the killing is a graphic example of a decline in "the quality of life in New York City."

"We're going right back to where we were," he told Henry. "... This homicide is reminiscent of the things that went on back in the 1970s, '80s, and '90s, and people ignore it."

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Kerik said he felt badly for former Mayor Michael Bloomberg's police commissioner, Ray Kelly, during the stop-and-frisk era.

"You know, they continued the policies that [Rudy] Giuliani put in place. It was aggressive policing, and I do understand that Mayor Bloomberg enhanced the stop-and-frisk, those numbers, substantially. Probably too much. There wasn't enough oversight there. [The stops] can be abused," Kerik said.

"But, at the end of the day, the men and women in the NYPD have to have the ability to do the job that they are here to do. And, when you take the tools away to do that job, crime is going to rise," he said.

Fox News' Morgan Phillips, Marta Dhanis, and Courtney Crawford contributed this report.