A jealous husband strangled his two young children with internet cables after he discovered his wife had been using online dating websites
, a court heard.
Petros Williams, 37, was angry and bitter when his wife Morengoe Molemohi left him after the breakdown of their relationship.
A jury was told he recorded a haunting video of his two children laughing and waving goodbye to their mother.
He labelled the video 'The End' and two days later he allegedly strangled four-year-old Yolanda and two-year-old Theo Molemohi with internet cables in a 'symbolic act of punishment.'
She had moved out of the flat they shared in Whalley Range, Greater Manchester, but returned daily to get Yolande ready for school and to care for Theo while Williams went to work as a finance officer for a housing company.
Mr Thomas said: 'On Tuesday 13th October, Miss Molemohi left the children with the defendant and returned to the hotel where she was staying.
'The next morning she went back to the flat to help get her daughter ready for school. The front door was locked from the inside. She had to let herself in through the patio windows. She found the defendant in the bedroom. He was lying on the bed with the two children.
'Miss Molemohi thought the two children were asleep. It was only when she reached out to them she realised they both had cables tied around their necks.
Mr Thomas said: 'There were notes in the flat. They were, in effect, suicide notes, saying goodbye to his wife and colleagues.
'If the defendant had intended to kill himself, he had not got very far.
He was still very much alive although he appeared unwell.
'The defendant killed his two children. It was a spiteful and selfish reaction to the breakdown of his marriage. It was a deliberate act and the prosecution say it was murder.'
Manchester Crown Court heard Williams left a sarcastic message attached to the computer which read: 'Mo, use the internet as much as you like, luv Petros.'
Williams, who denies two counts of murder, showed no emotion as the jury were shown a home video labelled 'Daddy, Yolly and Theo. The End video.'
The video, recorded as the children watched X-Factor on the Sunday night before they were killed, shows them waving at the camera saying: 'Goodbye mummy.'
A note found in the flat by the video camera read: 'Play the video we made for your memories. Thankyou Petros.'
The trial continues.