Police have named a man who was found dead in Manningham over the weekend.
Paul Ackroyd was 37 years old and from Bradford.
Detectives are keen to speak to anyone who was in the Gracechurch Street area of Manningham between 2am and 4am on Saturday February 23.
Mr Ackroyd was found in Jinnah Court at about 3.52am on Saturday and pronounced dead at the scene.
Four people remain in police custody.
Anyone who has any information which may assist this investigation is asked to contact the Homicide and Major Enquiries Team on 101 quoting crime reference 13190098637, or use the live chat facility at www.westyorkshire.police.uk, or contact Crimestoppers anonymously on 800 555 111.