Yost's department has been under investigation following the traffic stop beating of Floyd Dent a few months ago.
One of her former officers, William Melendez, was recently charged this week with the beating of Dent and was accused of planting drugs at the scene.
Yost gave the city 30 days in her resignation but was relieved of duty today, sources say.
Dent was pulled after he ran a stop sign on January 28. He admitted to blowing through the sign but not the cocaine police said they found.
He has said he saw officers plant the narcotics on his car and he took a lie detector test to prove his innocence. His lawyer says he passed.
The drug charges have since been dropped.
The 57-year-old auto worker has no criminal history yet was pulled from the car, tackled, put in a chokehold and beaten.No further details are available at this time, stay with FOX 2 for more information as it becomes available.