The investigation into Johnny Manziel's alleged assault of his girlfriend Colleen Crowley is being kicked to a grand jury ... which will decide whether or not to bring charges against the QB.
The Dallas Police Dept. has announced ... "The investigation of the domestic violence assault involving Jonathan Manziel, which occurred on January 30, 2016, has been completed."
"Today, a Class A misdemeanor Assault/Domestic Violence case has been referred to the Dallas County District Attorney’s office for presentation to the grand jury."
"The Dallas Police Department will not release any details of the investigation while it is pending grand jury presentation."
As we previously reported, Crowley told police Manziel hit her several times in the head during an argument which began at a Dallas hotel ... rupturing her eardrum in the process.
Manziel has previously denied the allegations -- telling TMZ Sports, "It didn't happen."
Investigators have said they have reviewed health records and surveillance footage from the hotel -- though they have not said what was on the video.