Petros Williams Mwashita, 37, is charged with killing his son, Theo Molemohi, 2, and his four-year-old daughter, Yolanda.

Their mother, Morongoe Molemohi, 30, who was recently estranged from her husband, found her unconscious children at a flat in Whalley Range , Manchester , on Wednesday morning last week.  They were pronounced dead a short time later.

Mwashita was found collapsed at the scene near his children and was arrested. He was thought to have taken an overdose.  A post-mortem examination found that the children had been strangled.

Mwashita appeared in the Manchester Magistrate’s Court on Monday wearing a white T-shirt and blue jeans.  He spoke only to confirm his name, age and address, and to indicate that he did not require an interpreter.

Kieran Henry, for the defence, made no application for bail. Mwashita was remanded in custody and will appear before the Manchester Crown Court for a plea hearing on January 4.

The Daily Telegraph reported late last week that a heartbreaking video showing the two children saying “Goodbye, mummy” before they were strangled has been discovered by the police. Detectives are studying the video, which was found in the flat in a prominent position, as if intended to be found.

The video, which is thought to have been made about 10 days ago, shows the children playing happily and watching television, the UK newspaper believes. The father is with the children in some of the footage. At one point in the video, the children turn to the camera and say: “Goodbye, mummy.”

Their mother, who is a 30-year-old student, said: “I take pride in knowing that they were polite, caring, happy babies. I will always remain proud to be their mother. Their lives were short, but they lived to their full potential. I love them very much and they will always be a beautiful part of me.”

Morongoe Molemohi and Petros Williams Mwashita have lived in England for about six years. – AP/Daily Telegraph.