Officers said they spotted a man acting suspiciously in Railway Approach, Worthing, on Thursday afternoon (April 26).
A police spokesman said the Worthing Prevention team approached the man who subsequently ran off in the direction of Worthing railway station. He was pursued on foot and later arrested.
Police said a 25-year-old man of no fixed address was arrested on suspicion of supplying a class A drug (heroin) and two counts of assaulting a constable in the execution of his or her duty.
He was taken into custody before being released under investigation.
Also on Thursday – shortly after 12.30pm – police and paramedics were called to a separate incident at Railway Approach, Worthing.
Police said officers attended the Grand Victorian Hotel where a man in his early 30s had been found dead. There were no suspicious circumstances.
The coroner for West Sussex has been informed and police are assisting with the coroner’s enquiries.