Jurors have been shown footage of a youth pursuing another young man immediately before his death.
The accused, aged 16 and subject to reporting restrictions, faces a murder charge at Hove Crown Court in connection with the fatal stabbing of Joshua Ingram at Seaford railway station on September 10, 2025.
He has admitted to manslaughter as an alternative offence.
He also faces charges alongside a 17-year-old and a 15-year-old of plotting to cause grievous bodily harm with intent.
The youngest of the trio, aged 15, additionally stands accused of helping a criminal, a charge the 17-year-old has already accepted.
CCTV recordings depict the defendant walking with a companion who has no involvement in the incident through Seaford town centre.
The defendant spots Josh and dashes across the road toward him.
The footage shows Josh wearing a black hoodie alongside a companion, with the defendant approaching from behind. A separate member of the public also appears in the recording.
Josh is then set upon on the platform at Seaford railway station.
After the assault, the defendant flees through the town centre.
Subsequent doorbell camera footage shows him handing over a bag containing the weapon and garments to the 17-year-old who has admitted to assisting an offender.
The case remains ongoing.
