Renee ZellwegerIt is really hard to recognize inPam’s Best Thing.

Now, Zellweger’s costars have revealed her transformation to the role. Zellweger stars as Pam HuppNBC’s upcoming reality series “True crime” will premiere on March 8. Josh Duhamel, Judy Greer,Katy Mixon and Glenn Fleshler

The story tells the real-life story of Hupp, who is currently serving a life sentence for the 2016 murder of Louis GumpenbergerAnd is the main suspect in the 2011 murder of Betsy Faaria.

Zellweger’s transformation into the role—which included a wig, facial prosthetics and a body suit—was so drastic that sometimes, the cast didn’t recognize her themselves.

“Renée is a method [actor],” Duhamel told CelebHomes News’ Daily Pop. So sometimes it was hard to tell whether it was Renee or Pam until you hear Pam laugh.

He continued, “Renée is one of the greatest ever and it doesn’t surprise me that she did what she did. It’s the best show she has ever done.