The Santa Clara District Attorney’s office likely will not charge San Francisco 49ers defensive lineman Ray McDonald with domestic violence against his pregnant fiancee, the San Jose Mercury News reported Friday.

The district attorney’s Office is expected to announce the decision soon and issue a report laying out the reasons, sources told the newspaper.

The newspaper said the case may be undermined by evidence that McDonald’s fiancee has been an aggressor in the relationship, including a May incident in which she drew a handgun on McDonald following an argument.

McDonald was arrested Aug. 31 on suspicion of domestic violence while celebrating his 30th birthday at his home with teammates and friends. Police said the alleged victim had “visible injuries.” McDonald lives at the home with his fiancee.

McDonald has continued to practice and play throughout as coach Jim Harbaugh, general manager Trent Baalke and CEO Jed York have said they would allow “due process” to play out.

Two court arraignment hearings have been delayed.

McDonald has 18 tackles this season.