Director general of police, Kulbir Krishnan ordered the suspension after receiving the departmental report placed by the IGP, (Law and Order), B L Buam on Wednesday.
The three suspended personnel, officer-in-charge of Mawryngkneng police outpost, head constable and a constable, would be booked under Section 304 of the IPC for the custodial death of 17-year-old Sngewlem Kharsati earlier this week, the sources said.
Kharsati's family alleges that he died after being brutally beaten in police custody.
Police had, however, denied the allegations and claimed that Kharsati succumbed to his injuries after some drivers beat him up when he was trying to extort money from trucks plying on the Shillong-Jowai National Highway on May 9.
The matter is being probed by the CID. The district administration has also ordered a magisterial probe into the incident.