ST. LOUIS • Prosecutors may never know just how much off-duty St. Louis police officer Michael Schinner had to drink before he drove the wrong way down a one-way street and crashed into an on-duty officer, critically injuring a passenger the day before Christmas.

Schinner, 27, refused to submit to a blood test to determine his blood alcohol content, and police did not apply for a search warrant to force him to do so.

Circuit Attorney Jennifer Joyce would not discuss Schinner's case specifically, but noted that prosecutors and judges are on-call to handle requests for search warrants at any time from police who suspect drinking is involved in crashes.

"Typically, the more serious the incident, the more likely I'm going to have a search warrant," she said. "If it's a serious accident or fatal, that's the type of case I would expect to see a search warrant."

St. Louis Police spokeswoman Katie O'Sullivan said she could not comment on why police did not seek a warrant for Schinner's blood, saying Joyce's office forbids the department from talking about cases once charges are issued.

Joyce said search warrants can provide evidence value for prosecutors pursuing DWI charges - but it's not the only evidence available.

In a statement, Joyce wrote: "Prosecutors pursue DWI charges when we have the required evidence to prove in court that a crime has occurred. For a DWI, this evidence can include officer and/or witness statements, crime scene evaluation, evidence found in a vehicle, statements made by a defendant, blood alcohol or breathalyzer results, etc."

Responding officers wrote in court documents that Schinner was speeding the wrong way along De Tonty Street near Tower Grove Avenue when the crash happened at 2:16 a.m.

He claimed no memory of the crash, appeared "disoriented and confused," had a strong odor of alcohol on his breath and refused to make any further statements to police after the crash, authorities said.

Two empty beer bottles were found in Schinner's car, one on the driver's side floorboard, according to court documents.

Schinner's passenger, Brian Cole, 28, sustained serious trauma to his head, including bleeding in his brain cavity. Cole was improving at a hospital and was upgraded from critical to serious condition on Sunday, O'Sullivan said.

Cole was planning to enter the Police Academy in January with the intent of becoming an officer, a police source said.

Along with DWI, Schinner has been charged with two counts of assault.

The on-duty officer, Darryl Monroe, was returning from an assignment in a police-owned Chevrolet Silverado when Schinner's car hit the police truck, authorities said. Monroe was treated at a hospital for hip and leg injuries and released. The Silverado had to be towed from the scene and sustained "heavy damage," O'Sullivan said.

Authorities may still have a way to determine Schinner's blood alcohol content. Schinner was treated for minor injuries and released from a hospital. If Schinner's blood was taken at the hospital, prosecutors can seek those results via a subpeona.

Joyce would not comment on whether her office will pursue Schinner's medical records, saying the move is part of an ongoing investigation.

Meanwhile, Schinner has been suspended indefinitely without pay. His medical benefits remain intact.

Schinner, who has been on the force for almost three years, was named District 8's Officer of the Month in May 2010 while still a probationary officer.

Judge Michael Mullen set Schinner's bond at $500,000 on Dec. 24. Mullen has since reduced it to $25,000. Schinner was released after posting 10 percent of his bond.

He is scheduled to appear before Judge Barbara Peebles at 9 a.m. on January 5 for a bond hearing.

He is also the subject of an internal affairs investigation. Once the investigation concludes, he could appeal any department decision by requesting a police board trial.

Robert Patrick of the Post-Dispatch contributed to this report