Afton Williamson on Sunday announced she would not be returning to the drama starring Nathan Fillion.

The Rookie actress Afton Williamson will not be returning to the ABC drama starring Nathan Fillion amid claims of sexual harassment and racial discrimination.

The actress, who co-starred on the cop drama from showrunner Alexi Hawley (Castle), ABC Studios and Entertainment One, on Sunday announced her departure from the show in a lengthy post on her verified Instagram account.

Williamson (Banshee, The Night Of) claims she experienced racial discrimination and racially charged inappropriate comments from the hair department as well as from the drama's executive producers starting with the pilot and continuing throughout the show's first season. What's more, the actress says the harassment was reported to Hawley and the showrunner never passed it along to human resources. Her issues escalated into sexual assault during The Rookie's wrap party, she said.

Sources say Entertainment One — the lead studio on The Rookie — launched and has an ongoing investigation into Williamson's claims. It's unclear if the investigation was opened before or after Williamson departed the show. News of her departure hit the press July 26 and sources say she made the decision to not return for season two a few days before that.

"The allegations involve a production from Entertainment One. In late June, eOne made us aware and informed us that they launched an investigation that is ongoing. The safety of working environments is a top priority for us, and we take this matter very seriously," an ABC spokesperson said in a statement.

"We take claims of this nature very seriously. We have initiated an independent investigation which is ongoing and as such, it would not be appropriate to comment at this time," eOne said in a statement of its own late Sunday afternoon.

ABC Entertainment president Karey Burke is set to meet reporters Monday during the network's time at the Television Critics Association's summer press tour.

Reps for showrunner Hawley did not respond to THR's request for comment.

The Rookie was picked up straight to series and renewed for a second season. Fillion — who plays a rookie cop within the LAPD — stars alongside Alyssa Diaz, Richard T. Jones, Mercedes Mason, Melissa O'Neil and Eric Winter. Key recurring players from season one included Mircea Monroe, Danny Nucci, Demetrius Grosse, David DeSantos, Currie Graham, Michael Beach, Shawn Ashmore, Cameron J. Armstrong, Sarah Shahi and Sara Rue.

Williamson's full post is below.