Elena Petrizzi was discovered unconscious and badly dehydrated by her father, 45-year-old Lucio Petrizzi. He frantically tried to revive her before calling paramedics.
Doctors at Ancona`s Salesi pediatric hospital on the Adriatic coast declared the 22-month-old brain dead three days later.
Police questioned Mr Petrizzi who said he was convinced he`d dropped his daughter at playgroup before heading to work.
He said, "I`d give my life to save her."
"I just don`t know what happened. I was convinced I had dropped her off. I locked the car and went to work. It is as if someone pulled the plug out of my brain."
The girl`s mother, who is eight months pregnant, says what happened to the father could happen to anyone.
Chiara Sciarrini fought back tears as she read a message on television over the weekend.
"I want to shout to the entire world how much my companion loved his daughter," she said.
"He is not to blame. He is always so busy rushing here there and everywhere."
"He was always busy himself with me and Elena. He is not guilty of anything. He is an exemplary father."
Organs from the girl were sent to hospitals in Bergamo, Turin and Rome.
According to Dr Francesca De Pace, there is always a high demand for children`s organs.
"The gesture of these heartbroken parents must be admired because through the death of their child, new life is born, new hope is given.
"It is an act to be admired, maybe an act to help them overcome this tragedy."
An autopsy will be carried out on Elena and prosecutors could still bring manslaughter charges against her father.