One his first day on the job, Dallas County District Attorney John Creuzot gave the oath of office to prosecutors and investigators in the 470-person office. He also gave some insight on how he will run the office.

"What I am asking you to do by taking your oath here today, is to join with me in another era of criminal justice reform," Creuzot said.

Creuzot told the group they would get more information soon about what they would decline to prosecute.

"What we have learned is that we have locked up many people who do not pose a threat to public safety," he said.

The new district attorney cited some examples when he spoke to reporters about what the office may not prosecute.

"Well, certainly first-time marijuana offenders and simple criminal trespass. We know that most of those people, obviously, they are poor, number one. Number two, they may suffer from underlying circumstances and problems such as mental health or substance abuse. And putting them in jail is not going to solve any of those problems," Creuzot said.

Creuzot takes over an office with several high profile cases.

Amber Guyger is accused of fatally shooting Botham Jean. The office also has the Sherin Matthews case, in which the girl's father is charged with murder, and her mother with child abandonment.

NBC 5 asked if there would be any changes in the prosecution of those cases.

"I don't know that the prosecutors that have been handling it will be changed," Creuzot said. "I mean obviously my set of eyes will also be on it -- on those cases -- but I don't anticipate, nor have I heard, maybe on some of the cases, there may be some change in prosecutors, but for the most part there won't be."