Sheriff's detectives and art experts are debating the authenticity of the drawing.
Investigators are probing deeper into the expanding mystery of the drawing attributed to Rembrandt reported stolen then recovered days later.
The artwork known as "The Judgment," was done in quill pen and ink and is about 10 inches by 6 inches. It disappeared Aug. 13 from the Marina Del Rey Ritz-Carlton in what investigators called a well-planned theft.
The drawing reappeared two days later, discovered in the office of the assistant priest at Saint Nicholas Episcopal Church in Encino.
Now, however, it appears investigators aren't sure if the drawing is even authentic.
"Is it a grand theft? Is it a petty theft? Is it a fraud? We don't know," said Steve Whitmore, spokesperson for the Los Angeles County Sheriff's Department.
"We have a lot of unanswered questions, so we'll get to the bottom of it."
The drawing was reported stolen by the Linearis Institute, which is based in the San Francisco area. But Whitmore said the institute has been unable to prove it even owns the drawing.
"We began to realize that nobody seems to know if this is an actual Rembrandt," Whitmore said. "We are going to maintain possession of the drawing until we can discover, at the very minimum, who owns it."
Darren Julien has an auction house in Beverly Hills. He explained how authenticating a Warhol required a trip to New York. He said a Rembrandt would need to be authenticated in the Netherlands.
"If something doesn't come with the proper authentication, or it's not part of the artist's portfolio, you either stay away or you're very suspicious of it," Julien said.
Before it was swiped, the drawing was on display in a hotel hallway with other famous artworks including some by Pablo Picasso according to one hotel patron.