Kansas City, Mo. ? Police have acknowledged that detectives returned only one of 50 calls made to them by the tipster who led to an eventual break in the case of a beheaded girl known for years only as Precious Doe.

“We dropped the ball,” Sgt. Dave Bernard, who led the four-year investigation into the killing of the girl whose headless body was found April 28, 2001, in a wooded area near a Kansas City park. Her head was found nearby a short time later.

The informant who led police to identify the girl last month as 3-year-old Erica Michelle Green and to arrest the girl’s mother and the mother’s husband was first in touch with detectives last year.

Michelle M. Johnson, 30, and Harrell M. Johnson, 25, of Muskogee, Okla., are each charged with second-degree murder and are awaiting trial.

After an internal review, police acknowledged Thursday that the tipster, Thurmon McIntosh, called them 50 times trying to convince them that he knew Precious Doe. Only three of the calls were logged in the case file and only once did a detective return a phone call to the tipster, the review found.

McIntosh’s calls were among 1,100 tips police received about Precious Doe over the four-year investigation.

“This case overwhelmed us,” Bernard said. “And it wasn’t the only case we were working. We had three murders the weekend Precious Doe was found. We started out behind and never caught up.”

Police acknowledged that McIntosh’s tips, had they been handled better, could have led them to an arrest earlier. But Deputy Chief Rachel Whipple said that doesn’t mean someone did something wrong.

McIntosh, 81, of Muskogee, Okla., made his 50th call to police on April 29. In that call, he offered information only the killer would know. McIntosh said the call followed a conversation he had with his grandson, Harrell Johnson.

“It made us believe this could be the one,” Bernard said, adding that he didn’t know then that McIntosh had called previously.

Police did follow up on McIntosh’s first call, Bernard said, but the investigation ended after detectives found that Michelle Johnson was receiving welfare payments for Erica Green in Aurora, Ill. When McIntosh called again, he told police his grandson’s wife had admitted that Precious Doe was her daughter and that her husband had killed her.

The detective believed he already had accounted for Erica, Bernard said. He also apparently misunderstood a detail McIntosh gave him: While the detective thought McIntosh said Erica was 1 year old when she was killed, McIntosh said he told the officer he hadn’t seen her since she was 1.