The 43-year-old woman who assaulted her Chai Chee neighbour also has a history of aggression towards her son-in-law and his family.

"(Ng) has been like that from the day I knew my wife... She's a violent person," Casey Sabrina Ng's son-in-law, Mr Lester Pereira, told The Straits Times.

Mr Pereira, 27, and his sister, Lynneth, 23, made police reports against Ng last year after incidents at the Bukit Batok flat where they live with their uncle.

Besides "causing a nuisance", Ng had tried to set fire to the entrance of their unit. She then threatened Ms Pereira with a chopper.

"She was not happy that my wife and I were not together at that point in time," said Mr Pereira, who is going through a divorce with Ng's daughter. Married for six years, the couple have a four-year-old daughter and a son who is turning two. His wife has another daughter, aged six, born out of wedlock.

Mr Pereira, who does contract jobs, first met Ng before marrying her daughter.

Ng had turned up at his uncle's home, where her daughter was then living. Fresh out of jail, Ng had no place to stay and no money for food.

Mr Pereira's aunt took her in and not long after, Ng started drinking and finding trouble with the family for no apparent reason, he alleged.

"I told my wife not to have her around. We couldn't live happily at all," he added. He was also told that Ng would enlist the help of others to beat him up, he said, adding that his mother-in-law did not like him.

Around 2013, his family lost contact with Ng for more than a year when she lived in Chai Chee with an older man she said was her uncle. But one day in 2014, Mr Pereira found her on his doorstep, drunk. When he asked why she was there, she broke down in tears - the older man had been injured. "She got frightened and ran away," he said.

Later that day, he said he found her taking drugs to "cool off".

"She drank and she took drugs in my house," he said, adding that she also hit his children to provoke him.

While Ng did not like many people, he said, she was "okay" with her daughter. Each time Ng got into trouble with the law, her daughter would bail her out. At first, Mr Pereira helped as Ng had promised to change. But once she stepped out of the police station, she returned to her old ways, he said.

"I told my wife, please don't bail her out. If she really has depression, she needs treatment." He said Ng has a certificate saying she has depression. But his wife persisted.

"I don't want anything to do with (Ng)," he said. "If she's outside, she'll hurt more and more people."

Seow Bei Yi