SAINT-OMER, France (AFP) - A hushed French courtroom on Wednesday viewed a video showing a defendant cuddling the 15-month-old girl she left to drown on a beach, in a murder she has blamed on witchcraft.

Projected onto a large screen, the two-minute video recorded on a smartphone shows Fabienne Kabou cooing the girl's nickname "Ada" as the baby gurgles.

The sight stunned the courtroom into silence, while the dead infant's father, Michel Lafon, looked away.

A few minutes earlier the court was shown two photographs of little Adelaide, one with the mother nursing the baby and another showing the girl wearing a little baseball cap.

Kabou, wiping away tears, said of the second picture: "She's 13 months old."

A computer expert told the court, however, that "no trace" of Adelaide appeared on Kabou's computer, while it did contain several pictures of unknown children and pregnant women.

He said he found no references to witchcraft, but rather searches about numerology.

Kabou, 39, on Tuesday gave a chilling account of the 2013 murder, telling the court it was as perfunctory as "going shopping".

She said she left her home in Paris and took a train to the northern resort town of Berck-sur-Mer where she asked passers-by about a hotel near the beach.

She said she played with Adelaide, before breastfeeding her until she fell asleep after which she took her to the beach and laid her at the water's edge.

"I understood the water was covering my daughter, my boots were in the water," Kabou said. "It was so dark the moon was like a spotlight."

She said she left Adelaide there and ran away. Prawn fisherman found the toddler's lifeless body the next morning.

Kabou grew up in Senegal in a well-off Catholic family before moving to Paris to study philosophy and architecture where she fell in love with Lafon, a sculptor 30 years her senior.

Described by her lawyer as highly intelligent, she told the court she had no other explanation for her acts but "witchcraft".

Kabou said she carried out the murder "perfectly mechanically, as if a part of me was anaesthetised" and returned home the next day.

She has said Lafon never wanted the child and questioned whether he was even the father.

On Monday, the accused said she had spent some €40,000 (S$60,000) consulting various "witchdoctors and healers" before carrying out the murder, and that she had suffered hallucinations.

However, Jean-Christophe Boyer, a lawyer for a children's group that is a civil party to the case, has accused Kabou of citing witchcraft and her culture as a defence strategy.

A court psychiatrist said her act was possibly triggered by a deep depression related to having the child.