Detectives investigating the fatal stabbing of Rohan Trotman in Peckham last year arrested and charged 19-year-old Yusuf Kallon within two weeks of the killing.
A jury heard how detectives proved Kallon had dumped his phone shortly after the murder, and spent hundreds of hours on intensive CCTV trawls to identify him as a suspect.
Detectives also revealed that Kallon was making desperate plans to flee, by making credit card payments to a holiday company in Spain, booking a flight to Sierra Leone and paying for a new fast-tracked passport.
On Monday, 3 June, a jury convicted Kallon of murder and two counts of robbery.
Kallon was found not guilty of possession of an offensive weapon.
He will be sentenced at the same court on 28 June.