A man suspected of killing his 4-year-old granddaughter last September has told investigators he ended the girl's life in a split second and has regretted the decision ever since.

Ronny Ron - who was Rose Pizem's paternal grandfather as well as her mother's live-in lover - and the child's mother Marie-Charlotte Renault, became prime suspects in her death after her body was found in a suitcase in Tel Aviv's Yarkon River.

Ron made his confessions during a taped reconstruction of Rose's murder, which was played Tuesday at the Petah Tikva District Court.

On the tape, Ron described how Rose repeated the word "disgusting" over and over again when he gave her a wafer to eat after picking her up from his mother's house.

"I told her 'arret', French for stop," Ron said on the tape. "And then... I gave her a flick, quite hard, it struck her in the face. I didn't feel good, I understood that she was sad, angry," Ron said.

Ron said he continued to wander with Rose, wanted to buy her ice cream. A little while later, he stopped her and held her up.

"I told her: 'Don't cry, don't be insulted, father loves you'... I hugged her tight. 'Father loves you', pardon, 'I love you'."

"Oh, oh, what I wouldn't give to have not delivered that slap to my baby. To give a slap to a child, God help me, even if God forgives me and society forgives me I cannot forgive myself... I ended her life and I ended my life in a split second without thinking," Ron said.

When asked by an investigator if he had thought of calling the police or a hospital, Ron said that he had not, and added, "I was frightened by what happened, frightened out of my mind."

The tape then continued with Ron's description of his suicidal thoughts following the murder.

He and Renault wept when the tape was finished, as did many others in the courtroom.

Rose was born in Paris in 2004 to Renault, a French Jew with relatives in Israel, and Benjamin Pizem, the child of a French mother and an Israeli father. At the age of one, Rose made her first visit to Israel. That was the first significant encounter Benjamin had ever had with his father, Ron, and the first time Marie had ever met him.