O'Brien was arrested on Feb. 10 and charged on May 19.

As a detective, O'Brien was involved in a 2014 Title IX investigation into now-convicted ex-MSU doctor Larry Nassar's sexual abuse. O’Brien was assigned to survivor Amanda Thomashow’s case, but her report did not lead to an indictment of Nassar.

Ingham County Assistant Prosecutor Debra Rousseau said in a 2018 report that O’Brien failed to “consult additional experts, despite being asked to do so.”

After over a year on paid administrative leave, O'Brien was demoted from the assistant chief at MSUPD to captain. She returned to duty on Sept. 8, 2020 as a captain for special projects after being on hiatus since April 2019.

According to documents, Michigan State Police trooper Andrew Golden pulled up behind O'Brien's vehicle to initiate a car assist, following Ingham County Central Dispatch airing a 'be-on-the-lookout' for her car. Golden then arrested O'Brien for an OWI, after further investigation.

O'Brien refused to take a chemical blood test. A search warrant was authorized, and she was transported to Sparrow Hospital where a phlebotomist obtained her blood sample.

On Feb. 19, lab results revealed O'Brien's blood content was 0.25%, more than three times the legal limit for driving, which is 0.08% in Michigan.

As O'Brien was transported, she was "extremely belligerent" and told Golden she will sue him.

"I will own up to the fact whatever I blew was over the legal limit," she said while in the patrol car, according to the police report. "I don't give a s⁠—⁠—⁠— if I get fired. I don't give a s⁠—⁠—⁠— if I get arrested for drunk driving."

Ingham County Prosecutor Carol Siemon requested a special prosecuting attorney from Michigan Attorney General Dana Nessel's office on Feb 22. Nessel's office retained the prosecution of the case.

Judge Hillman sentenced O'Brien to one year of probation, 40 hours of community service by the end of the year, counseling and ordered her to pay a $700 fine and $1,295 in fees and costs. She had to also issue an apology to the arresting office for her behavior, and she can't consume alcohol or drugs without a prescription, leave the state without court permission or possess a dangerous weapon.

"Ms. O'Brien was placed on leave with no assigned work duties immediately following her arrest by the Michigan State Police last February," MSUPD Capt. Chris Rozman said via email. "While on unpaid leave, O'Brien resigned from the MSU Police Department and is no longer an employee of the department or the university."

This article was updated to more accurately reflect O'Brien's role in the Nassar investigation.