A 15-year-old boy arrested after a teenager was stabbed to death in Leeds has been released without charge.
But officers investigating the death of Irfan Wahid, 16, have arrested another 16-year-old on suspicion of his murder.
West Yorkshire Police found Irfan with a stab wound after being called to reports of an assault in Harehills Lane at around 3.45pm on Friday.
He was taken to hospital for treatment but died shortly afterwards.
A post-mortem examination conducted on Sunday confirmed the cause of Irfan's death as a single stab wound to the chest, a force spokesman said.
He said: "A 15-year-old boy arrested on suspicion of murder has been released without charge.
"Today detectives arrested a 16-year-old boy on suspicion of Irfan's murder and he is currently in police detention.
"Police are still appealing for anyone who witnessed the incident or who has relevant information to come forward and contact police on 101."
On Friday, Detective Superintendent Pat Twiggs appealed for witnesses who may have filmed the attack on their mobile phones.
He said: "I am appealing directly to anyone who witnessed the incident or has information that could help our inquiries to come forward.
"It is also possible that people may have recorded footage on their mobile phones and I would again encourage those people to come forward."