Five men and three women, aged between 16 and 40, are being detained at various garda stations in Limerick and Clare.
Lee Slattery's body was found in a shallow grave at Knockalisheen on the outskirts of Limerick city last May.
The investigation is continuing and anyone with information is asked to contact Mayorstone Garda Station on 061-456980, the Garda Confidential Line 1800-666111 or any garda station.
