By the end of May, the U.S. Attorney's Office for the Eastern District of Texas will have a vacancy in its top spot.

U.S. Attorney Joseph D. Brown announced Tuesday that he plans to resign, effective May 31.

Brown said in a statement that he planned to pursue opportunities in the private and public sectors.

"I'm excited about the next chapter," he said. "There are many exciting opportunities on the horizon and some of those will become apparent in the coming days."

In 2018, President Donald Trump appointed Brown to the U.S. attorney position. Previously, he served as Grayson County district attorney.

"It has been the honor of a lifetime to serve as United States attorney and to work with some of the finest prosecutors and support staff in the country. I am very proud of our accomplishments," Brown said.

Brown is known as a staunch political conservative, but he also has won the respect of Texas criminal defense attorneys. He was the Grayson County district attorney from 2000 to 2018. Before that, he was an associate with Cowles & Thompson in Dallas.

He comes from a well-connected political family. His father, David Brown, was a state district judge in Sherman. His uncle, Paul Brown, was a U.S. district judge in Sherman.

Read more: Trump's Latest Texas US Attorney Picks Get Good Reviews from Criminal Defense Bar

The statement said that Joseph Brown led the office to play a role in an initiative against opioid abuse that cracked down on illegal prescribing and dispensing by doctors and pharmacies and on domestic drug supply chains. For example, he prosecuted "pill mill" physicians. The office also made efforts to stop the supply of drugs by extraditing defendants from Columbia for drug-related charges, the statement said.

"We must win the fight against opioid abuse in order to save our country," he said. "Players both big and small must meet equal justice under the law."

During his tenure, the office increased prosecutions by 24%, which included a 40% rise in violent crime prosecutions and 100% increase in illegal immigration prosecutions, said the statement.

It said that Brown created an appellate section inside the U.S. Attorney's Office, and violent crime task forces in the office's divisions in Sherman and Beaumont. He increased the number of disaster preparedness trainings for local law enforcement agencies.

Davilyn Walston, a spokeswoman for the office, didn't immediately return a call or email seeking an interview with Brown.