Prosecutors have been portraying Anthony as carefree and cheerful in the weeks after the child, Caylee, was last seen in June 2008, hanging out with friends and hitting the clubs. Caylee Anthony was reported missing a month later and her remains were found that December.
Anthony, 25, has pleaded not guilty to first-degree murder. Prosecutors contend she suffocated Caylee with duct tape. Anthony's defense team says the child drowned accidently in a family pool. If convicted, she could be sentenced to death.
Birch said he'd spent 30 years in the towing business as well as two years in waste management, and had come across deceased bodies at least eight times. He said he first noticed the smell coming from Anthony's' car on the fourth day her 1998 Pontiac was parked on his yard. The car had been towed after spending four days in an Amscot parking lot. It stayed there from June 30 to June 15, when Anthony's parents retrieved it.
"In my opinion and experience, the smell of decomposition is unique in comparison to rotten food or rotting garbage," Birch said.
The defense argued in its opening statement that the smell was actually from a bag of trash Anthony left in her car.
"The instant flash in my mind was `Oh, I know what that smells like,"' Birch said about noticing the odor.
Mallory Parker, the fiancée of Casey Anthony's brother Lee, was called to the witness stand by prosecutors. She described how she and Lee searched for Casey in Orlando bars in the summer of 2008 when her family hadn't seen her in many days.
But Parker also said that Anthony had a special bond with her daughter and at one point broke down in tears under cross examination when attorney Jose Baez asked here to describe the relationship between them.
"It was amazing," Parker said.
Casey wiped away tears during Parker's testimony.
Anthony's former boyfriend Ricardo Morales testified Thursday that she was cheery when she picked him and his friends up from the airport on July 15, 2008, about a month after authorities believe Caylee was last seen.
"She was the same as she always was," Morales said of Casey's demeanor the day before her initial arrest. "Happy. Smiling. Just as usual. Same Casey."
Morales dated Anthony from February to April 2008. He also testified that Anthony and Caylee regularly stayed nights at his apartment during that same time period.