Question about Đăng Đình Bách and vietnamese prisons in General.

The place i go to school at has given us assignmeants to make presentations about victims of human rights abuses. All fine and good, but i got chosen to take the case about Đăng Đình Bách, a supossed "enviormental activist" who was imprisoned in vietnam. Of course as whit all Information i hear about a socialist country i had my doubts. (To the suprise of no one, some of the first articles that apeared when i searched his name where from Voice of america and Radio free asia) After that you get less obvious propaganda, i.e. Amnesty international or The UN, but they mostly all claim the same thing: That Đăng Đình Bách and other "political prisoners" have been "falsely imprisoned" and suffer under "horrible conditions" inside prison. It is safe to assume he is not innocent (he was found guilty of tax evasion in the amount of 1.38 billion VND through his organisations) but i have found nothing disproving the allegations of Bad prison treatmeant. This does not eleviate my doubts of their statemeant, so im asking if anyone here has some scources showing if there is some Merritt to what is beaing said about the prison conditions or if it is as most of the time false