Without knowing anything about the political situation in Bangladesh, I can say that the run-around that local police have given his family would fit the patter

Without knowing anything about the political situation in Bangladesh, I can say that the run-around that local police have given his family would fit the pattern that has followed extrajudicial detentions elsewhere. At best, he has been detained by the government, at worst he has been abducted/murdered with their tacit complicity, and at the least one of these is believed to be the case by local law-enforcement.