Monte Kiffin will not return to the Dallas Cowboys in 2015.

Kiffin last season served as the Cowboys' assistant head coach/defense -- a nebulous title under which he served mostly as an on-field consultant. In 2013, he was the defensive coordinator for a unit that ranked among the worst in franchise history.

A source said that Kiffin, who turns 75 later this month, would like to continue coaching in some capacity.