DALLAS -

An expert for former Dallas Cowboys defensive tackle Josh Brent's defense says the blood tests used to argue he was drunk were precise, but wrong.
    
Janine Arvizu (ar-VEE'-zoo) testified Friday morning that the Dallas County crime lab did not properly process Josh Brent's blood tests after a December 2012 wreck that left a practice squad linebacker dead. Police say Brent's blood-alcohol level tested at more than twice the legal limit.
    
Arvizu accuses the lab of using potentially spoiled chemicals and incorrect equipment in the tests.
    
Judge Robert Burns barred her from testifying in detail about contamination or the type of tubes used to store Brent's blood. Prosecutors are to question Arvizu Friday afternoon.
    
The 25-year-old Brent faces up to 20 years in prison if convicted of intoxication manslaughter or manslaughter.