Aug. 6 (UPI) -- Oakland Raiders cornerback Nevin Lawson has been suspended for four games for violating the NFL's performance-enhancing substance policy.
Lawson announced the punishment Monday on Twitter. The five-year veteran signed a one-year contract with the Raiders in March during free agency. Lawson, 28, played his first five seasons with the Detroit Lions after being selected in the fourth round of the 2014 NFL Draft out of Utah State.
"I love my teammates, cherish the privilege of playing professional football for the Oakland Raiders organization and looked forward to starting my sixth NFL season with passion and hunger," Lawson wrote. "That is why it is so difficult for me to stomach what I recently learned, which will lead to me being suspended for the first four games of the 2019 NFL season."
Lawson said he "discovered" a test determined he ingested Ostarine, which is included on the NFL's banned substance list. He said he has never "knowingly taken" Ostarine.
Ostarine is used by bodybuilders to increase lean muscle mass and strength, according the the U.S. Anti-Doping Agency.
"Unfortunately, it does not matter, as I am responsible for knowing every single ingredient that goes into my body, and I apparently failed in this regard," Lawson wrote.
Lawson apologized to his family, teammates, fans and the Raiders organization.
"I can only promise to give my all when I am permitted to return to the field and will take even extra care in ensuring that no impermissible substance are consumed in the future," Lawson wrote.
Lawson was one of several cornerbacks fighting for a starting job this off-season for the Raiders. He had 53 tackles, 10 tackles for a loss, five passes defensed and a sack in 15 games last season for the Lions. Lawson has appeared in 62 games and made 64 starts during his NFL tenure. He has missed just two games since the start of the 2016 season.
The Raiders host the Los Angeles Rams in their first preseason game at 8 p.m. EDT Saturday at RingCentral Coliseum in Oakland. Lawson's Raiders team is featured on this year's edition of Hard Knocks, which premiers at 10 p.m. EDT Tuesday on HBO.