Woman Accused of Killing 4-Year-Old Boy With Garden Shears

A Chinese woman was due in court on Thursday accused of killing a four-year-old boy in Australia with garden shears before laying in wait for his grandmother and stabbing her to death.

Cai Xia Liao, 45, was allegedly having an affair with the boy's Melbourne-based grandfather Brian Mach, 61, whom she bound and gagged in his home on Tuesday morning.

Police allege she then killed four-year-old Alistair Mach as he lay in bed during a visit to his grandparent's house while his parents worked, stabbing him repeatedly in the head and neck with the shears.

Cai, reportedly in Australia on a tourist visa, is accused of waiting 10 hours for Mach's wife Mai to return home before attacking and murdering her with the same shears in their backyard.

A neighbour reportedly alerted the police after witnessing the second killing.

An out-of-sessions court hearing late Wednesday was told Brian Mach had recently broken off a relationship with the woman. It was not clear whether he was injured during the ordeal.

Reports said Liao made no comment in a police interview and declined to speak during the late night hearing.

She has been charged with two counts of murder and one count each of intentionally causing injury and false imprisonment, and was due to appear in the Melbourne Magistrates Court later Thursday.

Family friend Diana Teoh, who had known Alastair since birth, told the Herald Sun newspaper he was "very bubbly, a very good boy".

"They (Alistair's parents) are trying to be strong for the rest of the family but they are definitely very devastated," she said.

"We don't know what to tell our children too because they played with him all the time."