Indian police are working with detectives from neighbouring Bangladesh to investigate the suspected murder of a lawmaker from Bangladesh’s ruling party, police officials said on Thursday.

Mohammad Anwarul Azim, a member of Bangladesh’s Awami League party, disappeared in Kolkata this month while seeking medical treatment in the Indian city, according to police inspector Akhilesh Chaturvedi of West Bengal state’s Criminal Investigation Department.

Azim was reported missing on May 18 by family members, after they received text messages sent from his phone suggesting he had gone on business to India’s capital New Delhi.

Chaturvedi said security camera footage showed Azim entering a building in Kolkata with two men and a woman, and while his companions were seen leaving, he was not.

When Indian detectives entered the building this week looking for Azim, they found apparent blood stains in a bedroom and a sink. No body has been found.

“A special investigations team was formed to launch a search operation to find the politician,” Chaturvedi said.

Bangladesh’s home minister Asaduzzaman Khan told reporters in Dhaka on Wednesday that the lawmaker had been killed in a “pre-planned manner”.

Three men had been arrested in connection with Azim’s disappearance, he added, without giving further details.

“Police of the two nations are investigating the case,” he said.

Faruk Hossain, spokesman for the Dhaka Metropolitan Police, said Azim himself had previously faced at least three murder charges between 2000 and 2008, which were later dropped.