The mother of these two little children murdered by her ex-husband so that he was clear to start another family with his new girlfriend is demanding that they get the death penalty as their trial gets underway.

Zhang Bo, 27, started a new relationship with a younger lover who wanted to end it when she discovered that he was already married with a family.

But he promised to divorce his wife and when she told him that she also did not want the children, he threw them off a balcony to their deaths before feigning being upset and claiming that they must’ve fallen while playing.

Medics said that his daughter Zhang Ruixue, aged two, and his son Zhang Yangrui, who was just a year old had no chance of surviving the drop from the 15th floor of the tower block happened in the municipality of Chongqing in China in November last year. The little girl was killed instantly, and the little boy died a short while later.

According to court papers the man was desperate to marry his new love, and prepared to do anything to make her happy.

Prosecutors say she pressured him to get rid of them, even cutting her wrists on the day he killed them to show her frustration at not being able to start a new family with him.

The man then reportedly grabbed both children who were playing with their toys and threw both out of the window, before running downstairs seemingly grief stricken at what had just happened. He was filmed banging his head on the wall and crying uncontrollably, which the court now says was all a sham as the reality was that he was the killer.

He claimed at the time that he had been asleep when the children fell out of the window and said he was woken up by people shouting downstairs who had discovered the children’s bodies on a grass lawn.

The ex-wife of Zhang, named Chen Meilin, told local media that his new girlfriend Ye Chengchen “didn’t want Zhang to have children of his own blood”.

She said Zhang had started a relationship with her while he was still married, and divorced only later with custody settled so that the daughter would remain with her mother, and the son would remain with him until he was six years old.

The dead children’s mother Chen said: “At that time Zhang was on a video phone call with Ye, Ye slit her wrist, and then Zhang got scared. The phone was dropped, he picked up the two children, and threw them from the balcony.”

The indictment reads: “Ye Chengchen told Zhang Bo many times that she and her parents could not accept the fact that Zhang Bo had children. If Zhang Bo had children, Ye Chengchen could not be with Zhang Bo. Around February of the same year, the two agreed to murder them when they met in the Changshou District. Subsequently, Zhang Bo and Ye Chengchen plotted how they would kill the two children through face-to-face meetings and WeChat chats and eventually decided that it would be easiest to kill Zhang Ruixue and Zhang Yangrui by making them fall from a height.”

Local media reports that he has admitted he and Ye plotted to kill the children so that they could start a new family without any children from his former marriage.

The ex-wife said that her former husband had been a difficult father, very rarely showing any affection to his children and never learn to care for them for example in changing nappies. She said: “He almost acted as if she was not his child.”

She added: “The moment that I heard my kids were actually thrown out of the 15th floor by their father and the mistress, I couldn’t find any words to describe my feelings.

“I couldn’t imagine what my kids had experienced from the 15th floor to the ground: Were they desperate? Were they afraid?”

She had initially filed a civil case to go alongside the criminal case demanding compensation for funeral costs and emotional distress but has now changed her mind, and cancelled it, saying that she wants both of them to have the maximum penalty and to be executed for what they did.

The trial started yesterday (Monday 26 July) and the court decided to adjourn to consider its verdict.