(Image Credit: ABC News)

The one-of-a-kind statue of Dr. Seuss' "Lorax" is missing from his own backyard.

Seuss' widow Audrey Geisel, 90, and a groundskeeper noticed the statue missing from its place in the garden Monday morning at the La Jolla, Calif., family estate, the San Diego Police Department said.

The 300-pound statue was supposedly rolled onto an adjacent piece of property, public affairs Lt. Andra Brown said.

There are no leads or suspects, she said, and police are still looking for the statue.

The owners, who are worried that the irreplaceable "Lorax" will be melted down for the bronze, say there will be no questions asked if the statue is returned safely.

"I thought it was one of those pranks people pull on television, so I was like, 'Come on guys, where is it?'" Carl Romero, property manager of the Geisel estate, told ABC affiliate KGTV.

The statue, created by Geisel's daughter, has been in the backyard out of the public eye for 12 years, leading Romero to suspect an inside job.

"So it's somebody that's been working up on the property," he said. "I'm not accusing anybody. I'm not pointing fingers. I don't know."

The statue, valued at $10,000, is the only one ever made and the mold was destroyed after it was crafted.  The 2-foot-tall "'Lorax" had sat on a tree stump, with a plaque reading "unless."'

There are three similar statues, but none the same as the missing one. "If we find it in your garden and the police are involved, we're going to prosecute," Romero said.  "It belongs to Dr. Seuss. It's his character.  Everybody knows what it is. Let's return it, OK?"

A security system was in the process of being installed on the property but was not running in the time frame of the theft.

The recently popular orange creature who "speaks for the trees," from the children's book written by Dr. Seuss, who's full name was Theodor Seuss Geisel, is starring in an animated film featuring Danny Devito, Zac Efron and Taylor Swift in theaters now. Dr. Seuss died in 1991 at age 87.