The trial of Casey Anthony, who has been charged with murdering her 2-year old daughter Caylee, focused on Casey's imaginary friends and the nanny who allegedly had kidnapped the baby even as her brother testified that he had detected some potent odor coming from her car.

Lead investigator Yuri Melich took the witness stand on Wednesday and testified that he had interrogated Casey on July 16, a day after Caylee was reported missing by her grandmother Cindy.

Melich said Casey had told him that Caylee had been kidnapped by a babysitter called Zenaida Fernandez-Gonzalez, who she had met through a friend called Jeffrey Hopkins.

Casey had told Melich that Zenaida (Zanny the nanny) had also taken care of Hopkins' son.

When asked why she hadn't told anyone about the kidnapping, Casey told Melich that Hopkins and Juliette Lewis, her co-worker at Universal Studios, knew.

Melich said when he asked for Hopkins and Juliette's phone numbers, Casey had told him she didn't have their phone numbers with her at that moment but could get them.

Everything could have been fine except for the fact that neither Hopkins nor Juliette ever existed. They are all imaginary friends made up by Casey, who also pretended to her parents that she was working at Universal Studios although she never returned to her job after giving birth to Caylee in 2005.

Melich also testified that the police had later tracked down one Zenaida Gonzalez, who swore she never saw Casey or Caylee and later had sued them for defamation.

The investigator also said that when he had asked Casey why she hadn't informed the authorities for 31 days that Caylee was missing, Casey replied to him, saying she was naive and thought she could handle this myself, which obviously I couldn't.

And I was scared that something would happen to her if I did notify the authorities or got the media involved, or my parents, which I know would have done the same thing. Just the fear of the unknown. Fear of the potential of Caylee getting hurt, of not seeing my daughter again, Casey said.

Melich recalled Casey also swore at the end of the interview that she was telling the truth and had never mistreated Caylee or abandoned her anywhere.

The only thing that matters is getting my daughter back, Casey had told Melich.

Earlier on Wednesday, Casey's brother Lee Anthony also testified how he became stunned when for the first time on July 15 he heard from his sister that Caylee was missing for 31 days.

Lee said he met Casey on July 15 after their parent had discovered Casey's car at the impound lot. He said, like his parents, he noticed a very potent, very strong smell coming from the garage where his parents had parked Casey's car to air it out.

Lee said he asked Casey about where Caylee was and why wasn't she bringing her home.

Because maybe I'm a spiteful bitch, Lee recalled Casey telling him.

Lee said Casey also told him that Caylee was asleep at her nanny's house and didn't want to be disturbed.

He told the jury that he offered to go get Caylee or have his roommate do it. There was, in my mind, no excuse why anybody couldn't go get Caylee, Lee testified.

However, when Lee continued to insist that they see Caylee, the shocking truth tumbled out. She just looked at me with no reaction...Then at that time she told me that she had not seen Caylee in 31 days, that she had been kidnapped and that the nanny took her, Lee said.

The decomposed remains of Caylee, who disappeared since June 16, was discovered five months later, in December 2008, in a wooded area near Casey's parents' home by a meter reader who was relieving himself. Her skeletal remains were wrapped in a Winnie the pooh blanket and her mouth and nose were taped with a duct tape.

The prosecutors say Casey chloroformed Caylee and then put duct tape over her nose and mouth, suffocating the girl.

Casey's lawyers, however, claim Caylee was not murdered. They say the toddler accidentally drowned in the family swimming pool and George, Casey's father, helped her keep the death a secret.

Casey has been charged with seven counts, including first degree murder, aggravated child abuse and misleading the police in the death of Caylee. If she is convicted of first degree, she could be sentenced to death by the seven-woman, five-man jury.

The trial could take 4-6 weeks before a verdict is reached.