Justin re-joined Rugby for a third spell in May 2018 teaming up with new boss Carl Adams as player/assistant.
Marsden, 35, spent the previous two seasons under Adams at Stratford Town.
Marsden dazzled onto the scene near the start of the 2002/03 season as an 18-year-old after progressing through the youth team at Rugby, scoring on his full home debut against Stourport Swifts and putting in some outstanding performances.
Justin's pace, flair and staggering skill took many a Southern League team by surprise during his career and picked up a respectable tally of 10 in his first season with Rugby.
Built on his first season by scoring 35 goals in his three full seasons with the club as a senior playing before leaving with departing manager Tony Dobson in June 2005 to join Solihull.
Enjoyed his best spells of his career with Nuneaton Townas they climbed back up the non-league pyramid up to the Conference North and also featured for Leamington.
Justin re-signed for his second spell at Rugby in July 2013 from Barwell before leaving again in 2015 after two good seasons.
After his second stint, Marsden featured for Kettering and Bedworth before teaming up with Adams at Stratford.