A family is in mourning after the “vicious homicide” of their 1-month-old daughter in Battambang, an attack that came on the heels of an attempted rape late last week.

In a case described as “terrible” by investigators, a neighbour attempted to rape an 11-year-old girl as she was showering 20 metres from her family home at about 8:10 on Thursday night. According to Santepheap commune police chief Pang Roeun, the suspect turned off the light to the bathroom, entered and wrapped his hand over the girl’s mouth.

The girl wriggled free and screamed for her mother, Prak Phalla, who came to her aid. The suspect, previously married to a family member of Phalla, then allegedly picked up a heavy rock or a brick and slammed it against Phalla’s head.

Roeun said the suspect’s mother and grandmother tried to intervene, but when his grand-mother restrained him, the suspect threw her off, knocking her unconscious. Another male neighbour was also knocked unconscious by the suspect.

As the injured parties then scattered, the suspect then walked roughly 20 metres back to the family home where Phalla’s infant daughter and 4-year-old son were sleeping, according to James McCabe of NGO the Child Protection Unit (CPU).

“No one expected [the suspect] would run into the victim’s home and attack two sleeping children,” McCabe said.

One-month-old Soun Srey Nuth was killed almost instantly in the attack. Her brother suffered life-threatening injuries, but is now in serious but stable condition after being transferred to Siem Reap’s Kantha Bopha Children’s Hospital, where he underwent brain surgery.

Investigations are ongoing, but Roeun yesterday suggested the newborn could have been picked up from a hammock and hurled to the ground, as she suffered head injuries and all of her limbs were broken.

A distraught Phalla, reached yesterday and speaking from the hospital in Siem Reap, described the horrific scene encountered upon her return.

“When I returned home I could not hear the voices of my children … I rushed to pick up my little girl, but her body was limp and she was not crying, and I felt frightened for her,” she said. “I took my little baby and my son to the hospital and the nurse said my little girl was dead already. I could not say anything.”

Phalla added that if the suspect’s mother and grandmother had not intervened, she and her 11-year-old daughter might also have been killed. She hoped authorities would swiftly arrest the suspect and put him behind bars for life.

The CPU’s McCabe said that an “active manhunt was underway” across western Cambodia to catch the suspect whose name was withheld by district police due to the ongoing nature of the investigation adding that authorities were also cooperating with Thai police.

McCabe said the murder – which came after a notable drop in child homicides last year had been “devastating”, with four very young victims – aged between one month and three months, killed so far this year. “It’s very upsetting to see this … It’s incomprehensible why anyone would attack an innocent baby,” he said.

In a separate case late last week, a 10-year-old girl was found strangled to death on the bank of the Tonle Bassac river in Phnom Penh on Friday. The girl was walking home on a familiar stretch of road on Thursday afternoon when she was grabbed by a male suspect who attempted to rape her; she freed herself and ran, but was chased down.

McCabe said that 16-year-old suspect Horn Sokheng, who was known to the victim, was arrested later on Friday. Police will allege that he digitally raped and murdered the young girl.