A 25-year-old man discharged himself from hospital after an attack in Brighton last Thursday (April 15).
Officers received a report that a man was injured near the basketball courts by Kings Road, at around 12.30am.
The victim was taken to hospital for treatment and subsequently discharged himself.
A 31-year-old woman and a 35-year-old man -were arrested on suspicion of wounding with intent and have been released under investigation pending further enquiries.
Police are urging the victim to get in touch with officers so his full account can be taken.
Anyone with information is asked to contact 101, quoting 29 of 15/04.