The arrestee was identified as Dr Abdullah Al Mamun, the hospital’s registrar.
Police arrested Dr Abdullah from near the hospital around noon after being tipped-off, said Deputy Commissioner Harun ur Rashid of Tejgaon crime division of the DMP.
So far, 13 people have been arrested in connection with ASP Anisul’s death.
Anisul had been suffering from mental illness and was brought to Mind Aid for treatment on November 9.
The accused forcefully took the victim to the observation room of the hospital and beat him repeatedly, CCTV footage showed.
Also, the hospital staff informed Anisul’s family that he had fainted. And when the police officer's relatives took him to the National Institute of Cardiovascular Diseases, he was declared dead.
Later, Anisul's father filed a case at Adabor police station against 15 people on the following day.
Read Also: ASP Anisul's death: 2 Mind Aid staff confess