Thrissur: A remand prisoner who collapsed at the Viyyur District Jail here has died while undergoing treatment on Thursday.

The deceased has been identified as Resh Babu (35), a resident of Chittissery, Thrissur. His family has demanded an investigation, alleging that there were signs of physical assault on his body.

Police officials said Resh Babu was taken to the hospital after he reportedly collapsed due to a fever. As his condition was critical, he was admitted to the ICU.

Resh Babu was taken into custody by the Thrissur East Police on May 18. According to officials, he was shifted to Thrissur Medical College Hospital on May 28 after collapsing.

His father, Babu, said that when he saw his son while he was in police custody, there were no visible injuries on his face or body. However, after he was admitted to the hospital, the family noticed what appeared to be assault marks.

Babu alleged that his son's face and body showed signs of physical abuse. He said he did not know whether Resh Babu had been assaulted by police personnel or fellow inmates, but claimed that his son's teeth were loose and his lips and face were bruised and discoloured.

Relatives and friends said Resh Babu had been living with mental health challenges and would occasionally leave home without informing anyone. They said he had left home about a month ago and had been wandering around Thrissur city before being taken into custody.

The family also claimed that the police had been informed about his mental health condition. Despite this, they alleged, he was booked in a case and remanded to judicial custody.

Police have denied assaulting Resh Babu. They said an inquiry would be conducted to determine whether he may have been assaulted inside the jail. Post-mortem procedures have not yet begun.

The body is currently being kept at Thrissur Medical College Hospital. Officials said only the post-mortem examination can determine whether he suffered any physical assault and establish the exact cause of death.

The family has filed a complaint alleging suspicious circumstances surrounding the death.