The police is investigating one of its officers who is believed to have defied a court order for the release of detainee S Balamurugan, who died while in custody.

Inspector-general Khalid Abu Bakar told a press conference at Bukit Aman today that the investigating officer is being probed under Section 345 of the Penal Code.

"Police have started investigations under Section 345 of the Penal Code against the investigating officer for failing to abide by a court order to release the deceased (Balamurugan)," he said.

Section 345 of the Penal Code refers to investigations for wrongful confinement of person for whose freedom a writ has been issued.

Balamurugan, 44, was arrested on Feb 6 when he was found in the same car with two other men, one of whom was wanted by the police.

Lawyer Gerard Lazarus, who represented Balamurugan during his remand hearing, reportedly stated that the magistrate had ordered for the victim's release and for him to be taken to the hospital as he had coughed up blood during the proceedings.

Balamurugan, however, remained in detention and passed away in police custody at the North Klang district police headquarters on Feb 8.

Khalid also confirmed that police will also be recording statements from doctors involved in conducting the second post-mortem on the victim's body.

"We are still waiting for the first post-mortem result. We have not received it. The second post-mortem was conducted by the family and we only received a brief report.

"The second report is unclear, it was too brief. We will call the doctors involved to record their statements," he said.

Lawyers Latheefa Koya and N Surendran had last Sunday said the second post-mortem result has confirmed Balamurugan suffered multiple beatings while in police custody.

According to the duo, the cause of death is stated by the Hospital Kuala Lumpur (HKL) pathologist as "coronary artery disease with multiple blunt force injuries".

Lawyers have also called for the case to be classified as murder and for investigations to be carried out swiftly and independently.