The CHTC letter, sent by its Co-Chairpersons Sultana Kamal and Elsa Stamatapoulou to Home Minister Asaduzzaman Khan on Monday also demanded compensation for the family of the PCP --- Hill Students Council --- leader.
The CHTC expressed its concern over the incident as protests dubbing the death as a murder have continued.
Blockades on roads and waterways were enforced in Rangamati on Sunday. Leftist students' organisations have also demanded a judicial inquiry into Romel's death.
Romel, general secretary of the Naniarchar Upazila unit of the United People's Democratic Front- or UPDF-backed PCP, died at a hospital in police custody on Apr 19 after being arrested by the army on Apr 5.
The protesters have claimed he was tortured to death and his body was burnt to destroy evidence. The army has refuted the allegations.
In the letter to the home minister, the CHTC said there were allegations that Romel was 'brutally tortured' after his arrest.
It also alleged that even the local police and the state-run hospital in Naniarchar initially declined to take him in considering his ailing condition.
"It is of more concern that the authorities are passing the blame on to each other. The untimely death of a young student in an independent state and such activities of the law-enforcing agencies cannot be accepted in any way," the letter said.
"That's why we are demanding that the home minister form a high-level judicial investigation committee immediately and bring those involved with the incident to justice," the CHTC letter added.