Him Makhneur lifts the cloth of her hijab to wipe her eyes. She is mourning her son, Sen Savy, who died in custody at 19 years old in Prey Sar prison in the early hours of Wednesday morning.

Amid Cambodia’s sweeping crackdown on drugs launched in January, Savy was arrested – along with two of his friends – after he was caught smoking meth in a guesthouse on February 23. He was charged with using and possessing illicit substances. It was the second arrest for the Cham family from the capital’s Russey Keo district; his older brother was arrested a week before and charged with dealing.

Savy died awaiting trial, more than five months later, of “heart failure”, according to the prison’s clinic.

According to his mother, he had never been in trouble with the law before his arrest, but he had started “following his friends” in taking drugs.

Sen Romi, Savy’s sister, said he had a tough time in jail. He was beaten by other inmates, and prisoners needed money to pay for a sleeping space that wasn’t adjacent to the toilet. Unable to afford it, Savy was repeatedly stepped on and kicked as he slept by cellmates clambering to relieve themselves.

Makhneur visited her son a week before his death, on August 2. She claims he fell over three times as he walked on swollen legs to speak with her. He had confided in prison guards about his health issue – that swelling was painful, he couldn’t keep food down, and breathing was difficult. They told him to go to the prison’s medical clinic, but without help his mother says he couldn’t walk there.

On Tuesday night, he was taken to the clinic and given oxygen and an IV drip. Later that night, his condition deteriorated. He was taken again to the clinic, where he died.

“I pity my son, that I could not look after him,” Makhneur said.

Read more: Drug crackdown pushes courts and prisons to breaking point

Although she believes the prison neglected her son, she did not want to file a complaint. Instead, she had a message for the prison guards.

“Even though they are prisoners, they are all human. So you should take care of them, not ignore them like my son, causing his death,” she said.

“If my son has a problem with the law, they can sentence him. But they must look after him and provide treatment when he has a problem with illness.”

The family had not yet received any compensation, but San Keo, the spokesman for the Prisons Department who confirmed Savy’s death, said they should receive either 50,000 riel ($12) or 300,000 riel ($75).

Keo defended the prison’s actions but admitted “the problem with the health centre in the prison is the hygiene”. “Right now the number of people in the jail is increasing to make it crowded,” he said.

Chak Sopheap, of the Cambodian Center for Human Rights, said the right to adequate medical care was especially important for drug users in detention, “when an individual totally relies on the state for his or her care”.

“Mass arrests and overuse of pre-trial detention in the context of the government’s ongoing crackdown on drug offences have only worsened the existing conditions of detention at Prey Sar, a prison which fails to meet even the most basic international standards applicable to detention facilities,” she said in an email.

Over 9,000 people were arrested on drug-related charges in the first six months of this year during the government’s war on drugs. Meas Vyrith, of the National Authority for Combating Drugs, yesterday said that for the first 40 days of the campaign’s “second phase”, an additional 1,942 had been arrested.

He stressed drug users are sent to rehabilitation services, rather than jail, unless they are also caught in possession of drugs or dealing.

Although her son took drugs, Makhneur said he was never violent or disrespectful to his family, who remember him as talkative and playful. He was buried at a traditional Muslim funeral on Wednesday.

“We believe that if his action is wrong against the regulations of Allah, he can be punished,” Makhneur said. “However, we believe we can pray to Allah to forgive him of his sin.”