One of the things that complicated the case is that McDonald apparently called a San Jose police officer either before, or about the time that the 911 call was made and that officer went to the home.
Reliable sources inside the police department said the officer also works as security at 49ers games.
It was unclear if he was on duty or off duty at the time, but police sources said he should not have gone to the home and that he should have advised McDonald to call 911 if he didn't. Calls placed to San Jose police by ABC7 News were not returned.
The Santa Clara County district attorney's office also declined to comment.
The district attorney's office now has the San Jose police investigation and they'll have to see if they have enough to prosecute this case in court and if they can take this case to trial.
The district attorney will now decide whether to charge McDonald with physically abusing his fiancee, or not to prosecute him, or prosecutors will conduct their own investigation with the evidence that police have collected.
It was Aug. 31 when McDonald was arrested at his birthday party at home. A 911 call said he was abusing his pregnant fiancee.
It's been a lengthy police investigation. Lawyers said there's good reason for the delay -- the Ray Rice case. The ex-Baltimore Ravens star is in the national spotlight because of his own domestic violence problems.
Police wanted to be sure they covered everything before sending their report to the district attorney's office, another reason may be that McDonald's fiancee does not want to testify against him in court.
Colsaria Henderson is with Next Door, a support group for domestic violence survivors.
"I think it's completely normal what we see in domestic violence," Henderson said. "Most of the time, they don't want to end their relationship, but they want the abuse to stop."
McDonald's teammates who were at the party reportedly have also told investigators they saw nothing.
But attorney Steven Clark says if the case is charged, they will be called to testify even if they didn't see any actual abuse.
"All 49ers at the party could be very important witnesses at trial because they could testify on what led up to the allegation," Clark said. "If there was nothing that led up to it, that's good for Ray McDonald, but if there was arguing before the incident that could also be highly important."
Police did not say if they even made a recommendation one way or the other. And there's no telling when the district attorney will make his decision.
VIDEO: 49ers wait on due process to decide if McDonald plays