Dec. 20, 2008  -- The bones and skull found near the home of missing toddler Caylee Anthony have been determined to be the skeletal remains of the little girl, police concluded Friday.

Using DNA testing, officials identified the remains of a young girl found last week as the missing Florida toddler. Caylee's mother, Casey Anthony, is being held on first-degree murder charges.

The bones showed no evidence of trauma before Caylee died, and the death is being ruled a "homicide of undetermined means," said Orange County chief medical examiner Dr. Jan Garavaglia. The medical examiner has asked for toxicology tests to be performed on the remains.

The announcement brings just one tragic answer to a mystery that has gripped the nation since Casey reported the 2-year-old missing a month after she disappeared in June. It is not clear whether Caylee died before or after her third birthday on Aug. 9.

Caylee's remains, including a skull, were discovered in a wooded area less than half a mile from the Anthony home in Orlando, Fla on Dec. 11. Police have since found "most of [a] skeleton," Orange County Sheriff's Department spokesman Carlos Padilla told ABC News.

According to Padilla, the child's final resting place was in a section of woods people regularly use to dump trash and "bury their pets."

The discovery of evidence that the scene that was linked to the Anthony home prompted police to execute a search warrant on the home last week. Police were seen removing boxes and bags of evidence from home.

The skull fell from a bag that was found at 9:30 a.m. by an Orlando utility worker. The worker then reported it to authorities. Click here to hear the 911 call.

That worker had called police three times to urge them to search the area back in August, but after police responded twice to investigate, no body was found.

CLICK HERE for a timeline of the case.

Preparing for the Worst

With Caylee's body positively identified, attention turned towards her mother, 22-year-old Casey Anthony, who was charged with the toddler's murder in October.

Casey Anthony was arrested the day after she reported Caylee missing on charges including child neglect. She became a person of interest in the little girl's disappearance after police found traces of chloroform and strands of hair similar to Caylee's in the trunk of a car last driven by Casey Anthony.

Anthony was officially charged with first-degree murder Oct. 14. She has pleaded not guilty to charges ranging from first-degree murder to lying to investigators. She faces life in prison if convicted.

The discovery of a body was not an unanticipated possibility for Casey's defense attorney Jose Baez, Baez's spokesman Todd Black told ABC News last week.

"From the beginning we started preparing for the worst," Black said. "We were working under the assumption that a body could be found."

It was the position of Casey Anthony all along, the one that Baez represented in court, that Casey gave up the child to "a third party," Black said.

While members of the prosecution have been sifting through evidence ever since the remains were found last week, Baez was twice rebuffed in efforts to gain access to the crime scene in court by Judge Stan Strickland, who said he could not allow access until the remains were identified.

Baez had called in six experts, including a forensic pathologist, an anthropologist and an entomologist in preparation to examine the scene, but had to fly them out before the chance was given for them to examine the evidence.

On Wednesday, the police brought in their own entomologist and anthropologist.

Mysterious Tipster Called Back in August

The man who found Caylee's remains made three calls tipping officials off to the area in August, Orange County Sheriff's Office spokesman Angelo Nieves said in a news conference Thursday.

Police believe utility worker Ray Kronk, 46, returned to the area last week "out of curiosity." He is not a suspect in the case, and police do not know if he had any prior association with Caylee's mother, Casey Anthony, who is being held on murder charges, Nieves said.

"This is just a decent citizen," Padilla said. "He sounds credible. He doesn't sound like he's making this up."

"His participation in this matter is strictly as a concerned citizen with a sharp eye, good instincts and perserverance," said Kronk's lawyer David Evans in a news conference yesterday. "He has no connection to this case, to the Anthony family or any of the proceedings that have gone on before."

Kronk called in a tip on Aug. 11 but only told police the general area where he saw a gray and black bag and did not meet the responding detective, Padilla explained. The detective did not find anything suspicious and cleared the area. Kronk called again on Aug. 12 and 13, at which point police returned to the scene but again did not find anything to raise their suspicions.

Padilla told ABC News that police are investigating the "thoroughness" of the response, but said the area had a significant amount of water flooding many parts.

"We're trying to make sure -- is it possible that we missed an opportunity to locate these remains back in August?" Padilla said.

Frustrating, Curious Investigation

The case began with an emergency call from Casey Anthony's mother, Cindy Anthony, in mid-July.

On the tape, she is heard frantically telling emergency operators, "I can't find my granddaughter. ... There's something wrong. ...I found my daughter's car today and it smelled like there's been a dead body in the damn car." Casey Anthony then got on the phone and reported she may have a missing child.

Cindy Anthony later retracted that statement, saying that the smell in the car could have been from garbage.

As investigators would quickly learn, this would only the be first of many twists and story changes in the curious case. CLICK HERE for a timeline of the case.

Lies, Half-Truths and Incomplete Information

Since their investigation was launched on July 15, some Orange County officers have become well acquainted with the frustrations of following leads based on incomplete information, half-truths and what one officer said were "smoke bombs."

In the original version of events, Caylee's mother reported her missing to police, saying she had dropped the child off at a babysitter's house on June 9. When she went to pick the child up, both the child and the babysitter had disappeared.

Casey's parents both corroborated the story until a bond hearing on July 25 when Cindy Anthony said that the last time she saw the child was not on June 9, but on June 15, and that she had just been confused.

When police questioned Casey Anthony about her daughter prior to her arrest, they say Anthony misled them multiple times.

The Phantom Baby Sitter

The defense has maintained since Casey's arrest that she gave Caylee up to "a third party" -- a babysitter named Zenaida Fernandez-Gonzalez.

When Casey took police to the apartment where she said Gonzalez lived, they found that no one had lived in the apartment for five months.

At that time, lead investigator Yuri Mellich said, "I am not disregarding that this person may or may not exist, but Casey Anthony's friends and family have never met this person."

After an extensive search for Gonzalez, a woman with the same name came forward in September to tell authorities she had never met Casey or Caylee. Police cleared her of any involvement.

The Forensics Reports

Scientists found evidence of body decomposition and traces of chloroform in Casey Anthony's car trunk, according to forensics reports released in October.

Lab reports from the FBI found that a hair strand in the trunk showed "characteristics of apparent decomposition." The hair is "microscopically similar" to hair strands found on Caylee's brush, but the report said it could not conclusively say the hair in the trunk came from the missing girl.

Casey had been considered a "person of interest" in her daughter's disappearance since mid-July after police reported in a bond hearing that they believed they found that evidence of decomposition in the car.

Casey's Curious Attitude

But what unsettled investigator Padilla more than Anthony's imprecise information is her overall attitude during the initial phases of the investigation.

"She has shown no emotion," Padilla told ABCNews in July. "That's unusual. At the time of the interviews ... she didn't seem concerned and that made this case much stranger."

"She spoke to deputies like she was talking about baseball. How do you get through to someone like that?" he added.

But Anthony revealed the entire range of emotion in videos of jailhouse conversations between her and her parents which were released in early December.

In the more than 300 minutes of video released by the Orange County Sheriff's Department, Casey Anthony is shown laughing, crying and growing frustrated with the investigation and her family's questions.

When her mother, Cindy Anthony, confronted her with lead Detective Yuri Mellich's suspicions that she had had something to do with Caylee's disappearance, her daughter dodged the issue.

"Yuri [Mellich] has it set in his mind. He thinks you've done something to Caylee," Cindy Anthony told her. At that point, her daughter got up and, when she returned, steered the conversation in a different direction.

Casey Anthony also said that she knows the conversations are being recorded and said,"there are things [she] directly needs to say" to each of her parents.

And to Caylee, Casey asked her mother to pass along a message that "Mommy loves her very much, and that she's the most important thing in this entire world to me. And to be brave."

Orange County Sheriff Kevin Beary said his office is now working "to bring this case to a conclusion and get it prepared for court."