The NYPD has a new top cop. Dermot Shea is now the 44th police commissioner for New York City.

Monday was his first full day on the job.

The former chief of detectives fills the seat vacated by James O'Neill, who is retiring from the force after 36 years. Mayor Bill de Blasio says he knew Commissioner Shea was the right person to take on the helm and lead the NYPD into the future.

His nearly 30-year-career started in 1991 as a patrolman at the 46th Precinct in the Bronx. This was a time when violent crime and drugs were rampant.

Commissioner Shea says he's committed to a safer city. However, Shea faces a lot of challenges as he takes the reigns of the NYPD.

"I believe we stand on taking our nation's biggest city and making every neighborhood as important, where every child can grow up without the threat of crime," said Commissioner Shea.

He must continue to keep crime rates low while also contending with looming bail reform as well as pressure to reduce arrests. He says he will continue to strengthen the relationship between the NYPD and the community through neighborhood policing and outreach.