Richard Smith was tabbed as linebackers coach, with Andy Sugarmen hired as an offensive assistant, and Kevin Lartigue administrative assistant.
Smith, 47, spent the past six seasons as a linebackers coach for Mariucci in San Francisco. During Smith's tenure, four of his linebackers were selected for the Pro Bowl -- Julian Peterson this past season, Winfred Tubbs in 1998, and both Ken Norton Jr. and Lee Woodall in '97.
Sugarmen, 30, was on Mariucci's staff for five years in San Francisco, the last three as an offensive assistant, after working as the offensive quality control in his first two seasons.
Lartigue, 35, joins the Lions after six seasons in San Francisco, where he started as the assistant equipment manager in 1997, and was promoted to equipment manager the following year.
Mariucci had a 60-43 record in six years with the 49ers. He was fired on Jan. 15, three days after a 31-6 loss to Tampa Bay in the divisional playoffs last month.
The Lions fired head coach Marty Mornhinweg on Jan. 27 and targeted Mariucci, who was born and raised in Iron City, Mich.
2014: The Year in Music [PHOTOS]