Raheem Samuel complained of feeling unwell and had a cardiac arrest at his home in November last year.
He died in hospital three days later, Leicester Live reports.
It is believed the cardiac arrest was triggered by a stab wound to his back which he had sustained the previous April, Leicestershire Police said today.
The force said it launched a murder inquiry earlier this year after ‘specialist medical inquiries’ concluded his death had been caused by one of a number of stab wounds.
Today, officers appealed for help piecing together the circumstances which led to Mr Samuel being wounded.
The force said it had good investigative reasons for the decision to keep the investigation out of the public domain until now.
It said officers spoke to Mr Samuel, who lived in the Humberstone Road area of the city, when he was first admitted to hospital in the early hours of Saturday, April 6 last year.
It said he did not provide any information about how he came to be injured or who was responsible.
However, he did volunteer that the incident had happened ‘in town’, which detectives believes refers to Leicester city centre.
He was discharged from hospital the following day.
The senior investigating officer, Detective Chief Inspector Tony Yarwood, of the East Midlands Special Operations Unit, (Emsou), said: “While I appreciate, it’s unusual to wait so long to publicly announce a murder investigation, going public sooner could have jeopardised those specific inquiries we wanted to carry out and our best chance at that time of finding out what happened to Raheem.
“Please be assured we have been doing everything we can to find the person or people responsible for Raheem’s death and that we continue to do everything we can to find answers for Raheem’s family.
“This has been a very challenging and complex case, but we continue to work to find out what happened on that night back in April 2019.
