The transfer deadline has passed, but clubs can still sign players who are currently out of contract.
According to Sky Sport Italia, Mariga was training with the Parma players at Collecchio this afternoon.
The 27-year-old Kenya international is a free agent after his contract with Inter expired in July.
He had several spells in a Parma jersey, from July 2008 to January 2010, then returned on loan from Inter in January 2012 for six months and all of last season.
Mariga ended his over two-year self-imposed absence from Harambee Stars when he was recalled by axed Belgian head coach, Adel Amrouche for the 2015 Afcon preliminary qualifiers against Comoros.
He returned to the squad in the next round against Lesotho where Kenya crashed out of the competition after losing 1-0 on aggregate early last month.