His education began at UCLA, where he graduated in 1983 with a Bachelor of Arts Degree in Theater[1] and also won the Natalie Wood Acting Award.
[2] His most notable role has been that of Chief of Detectives Kenny Moran on the hit television series Law & Order: Criminal Intent.
Pniewski appeared as legendary football coach Bobby Bowden in the film We Are Marshall and co-starred in the CBS/Hallmark Hall of Fame production Front of the Class.
Additional credits include Big Love, Thief, The Riches, Miami Vice, The Ultimate Gift, The Sopranos, Madam Secretary, Blue Bloods, CSI: NY, Conviction, Warm Springs, Buried Alive II, Spaceballs, One Tree Hill, CSI: Miami, ER, Runaway Jury, From the Earth to the Moon, Ray, Remember the Titans, NCIS: New Orleans and Two Soldiers, the 2003 Academy Award winner for Best Live Action Short Film.
His credits include Xerox, Ford, Buffalo’s, Wal-Mart, TNT, Bell South, Sprite, CNN, McDonald's, UPS, Hills Brothers, Georgia Power, Publix, Wachovia, Sudafed, Zoo Atlanta, Chevrolet, The Atlanta Thrashers, Miller Lite, SunTrust Bank, GTE, and Blockbuster Video.