A murder investigation was launched on Thursday, 18 November after police were called to London Road, close to West Croydon Railway Station, at 6.41pm to reports of a fight involving a number of people.
Officers attended but no suspects or victims were found.
Shortly after 7pm, police attended a south London hospital after a 14-year-old boy self-presented with stab wounds.
Despite the efforts of doctors at the hospital, the boy died a short time later.
The boy was later formally identified as 14-year-old Jermaine Cools. A post-mortem examination gave Jermaine’s cause of death as multiple stab wounds.
There have been no arrests; enquiries continue.
Detective Chief Inspector Richard Vandenbergh, of the Met’s Specialist Crime Command, said: “We know that this was a murder which happened in a public place in the middle of a busy, commuter time and people will have witnessed Jermaine being attacked. I am asking for anyone who was in the area to cast their minds back to last Thursday.
“Were you at or travelling past the station at around 6.40pm? Did you see anything that might help police find the people responsible for Jermaine’s murder?
“Jermaine was a central member of his family, and his parents have been left devastated and without a son. At the very least, they are owed an explanation for why their son was killed, and police will continue to work relentlessly to ensure the people responsible are held to account.
“If you can help, please get in touch with my team or leave information completely anonymously with Crimestoppers.”
Any witnesses or anyone with any information is asked to call police on 101, quoting reference CAD 6179/18Nov, tweet @MetCC or call Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org.
Information, including any footage and pictures, can also be provided anonymously via