Milwauke ? Cincinnati Reds pitcher Brian Shackelford was arrested early Thursday on suspicion of third-degree sexual assault.

The 29-year-old player was arrested shortly after midnight at Miller Park, where the Reds played the Milwaukee Brewers on Wednesday night, police spokeswoman Anne E. Schwartz said. She declined to provide details on the arrest other than to say it involved a woman Monday.

“It’s an ongoing criminal investigation,” she said.

Shackelford was ordered to appear at the Milwaukee County District Attorney’s Office on Aug. 21, Assistant District Attorney Ken Berg said. Prosecutors have not issued any charges, though the investigation will continue, he said. He was released from jail Thursday afternoon.

The Reds optioned the pitcher to the minors and said they will not discuss the case because of pending legal proceedings.

“We recognize the seriousness of the matter and do not condone behavior of the type alleged,” the team said. The Reds left Milwaukee after the game and were in Atlanta on Thursday night.

Third-degree sexual assault is a felony in Wisconsin, carrying a maximum penalty of 10 years in prison and a $25,000 fine. The Reds sent Shackelford to Triple-A Louisville and brought up Mike Gosling.