Investigators have discovered a bone that "may be related to" the case of missing 10-year-old Zahra Baker, police said today.
Police will send the bone to a medical examiner's office to determine its relation to the case. Its discovery marks the first possible physical remains of the disabled North Carolina girl found since she was reported missing on Oct. 9.
The bone was found after police reportedly searched an area near where the girl's prosthetic leg was uncovered last week.
The find comes a day after the disclosure of jailhouse letters, apparently written by Zahra's stepmother, Elisa Baker, 42, in which she claims police know exactly where the girl is.
The letters maintain neither Elisa Baker nor her husband, Adam Baker, killed the disabled girl, but that Zahra's father did something "horrifying" after the girl was dead.
Police in Hickory, N.C., where Elisa Baker is being held on an obstruction of justice charge, said they had seen images of the letters but couldn't verify that she wrote them without looking at the originals.
Deputy Chief Clyde Deal told ABC News that the handwriting was "similar" to hers and the content matched some of what the woman has been telling police.
"I don't necessarily have any reason to doubt [that Elisa Baker wrote the letters], but I can't say that she did write them either," Deal said.
The letters, obtained by ABC News, appear to shift any blame from Elisa Baker to her husband Adam Baker.
"We really didn't kill her, but what he did after the fact is kinda horrifying," Elisa Baker wrote to crime memorabilia dealer Eric Gein from jail. "[It] makes me scared of him. So I probably am gonna go ahead and file [for divorce]. I have lost my whole life anyway."
Elisa Baker reported her stepdaughter missing on Oct. 9 and was arrested a day later on unrelated charges. She was later charged with felony obstructing justice for allegedly writing a fake $1 million ransom note in relation to her daughter's disappearance.
Gein, who runs the website SerialKillersInk.net, told ABC News he contacted Elisa Baker by letter weeks ago under an assumed name. The letters he received in return, first reported by AOL News, describe strained life in the Baker home. She allegedly signed one letter, "Dark Love Always, Elisa."
Further down the page between doodles of candles and a spider she writes, "Goth's Rule [sic]" and "Vamps Rule!" The comments are similar to those made on a MySpace page believed to belong to Elisa Baker.
Though police have been searching for Zahra's remains for weeks, Elisa Baker claims in the letters, "The cops know where she is and what he has done," apparently referring to her husband.
"[Adam Baker] knows what happened to Zahra, and yet I'm the one in here at least for now," she writes.
In the letters, Elisa Baker now claims Adam Baker actually wrote the phony ransom note.
A return address on an envelope also obtained by ABC News from Gein features Elisa Baker's name and a P.O. box associated with the Catawba County Sheriff's Department, where she is being held.
Scott Reilly, a court appointed lawyer for Elisa Baker, did not immediately return calls for comment from ABC News.
Police believe the girl -- who lost her left leg and hearing in a childhood battle with cancer -- is dead, but have not been able to locate her remains after weeks of extensive searching that focused on former homes of the Bakers, a nearby landfill, some mulch piles and a wood chipper. Investigators were able to locate the girl's prosthetic leg last week.
Adam Baker was taken into custody late last month on unrelated charges including assault with a deadly weapon, but is currently free on bond. When he returned to his Hickory home Tuesday, onlookers heckled him, exclaiming that he should be in jail, ABC News' Charlotte affiliate WSOC-TV reported.
Outside of Zahra's parents, who said they last saw her in bed the morning she was reported missing, authorities have only been able to find a single witness, a furniture store owner, who said they had seen the girl in more than a month before she vanished.
Hickory police said that early in the investigation Adam Baker was cooperating fully, but county officials remained suspicious of him.
Officials first became involved in the case on Oct. 9 when the Bakers reported a small fire in their back yard. It wasn't until later that day that they said they noticed their daughter was missing with her prosthetic leg, although her hearing aids had been left behind.
In a 911 call made by Adam Baker, he claims he saw Zahra in bed at 2:30 a.m. that morning. But in an interview with "GMA" two days later, Adam Baker said he hadn't seen the girl since early Thursday morning due to a hectic work schedule. In the same interview, he said that it was possible his wife, Elisa Baker, was involved in the girl's disappearance.
As the search dragged on, several neighbors and some family relatives came forward to claim Zahra Baker was repeatedly mentally and physically abused by her stepmother.
In one photograph from early August, obtained exclusively by ABC News, Zahra Baker is seen with what the photographer and family friend Brandy Stapleton said was a black eye. Stapleton said it was the last time she saw the girl.
Bobby Green, a former neighbor, told reporters early in the investigation that Zahra frequently had bruises but that Elisa Baker would always explain them away. "It's always she fell down, or she rolled out of bed or she didn't have her leg on right and couldn't walk right and fell. It's always Zahra's fault, for her injuries," Green said.
Brittany Bentley, a relative of Zahra's, told CBS News the girl "was beat almost every time I was over there for just the smallest things" by her stepmother.
The latest major break in the case came last week when police were able to locate Zahra's prosthetic leg in a brushy area a few miles from a former home of the Bakers. The discovery came just hours after police announced that Elisa Baker had been providing information to investigators.
Though police were aware Adam Baker had a warrant out for his arrest on unrelated charges, they did not take him into custudy until late last month because he had reportedly been cooperating with police.
ABC News' Yunji de Nies contributed to this report.