A key witness took the stand Thursday in the DWI murder trial of Michael Grasing.

Thomas Mott, of West Babylon, a high school friend of Grasing, testified Thursday.

Mott told the jury about speaking with Grasing on the night of the crash that killed 18-year-old Brittney Walsh, two years ago. He said Grasing was not slurring his speech during phone calls earlier that night, although detectives said Mott initially told them the opposite was true. 

Prosecutors say Grasing's blood alcohol level was four times the legal limit, when he crashed into Walsh's car on Montauk Highway in Lindenhurst.

Walsh died two days after her high school graduation.