The person arrested over the shooting of a 14-year-old Nottingham girl has been released without charge.
Danielle died of a bullet wound to the abdomen
Danielle Beccan was killed in an apparently random shooting as she walked home from a funfair with a group of friends.
Danielle was hit once in the abdomen when a number of rounds were shot from a moving car.
Police have described the killing as "senseless" and are trying to establish if it was a case of mistaken identity.
The schoolgirl died yards from her home in the St Ann's area of Nottingham.
Assistant Chief Constable Sue Fish said: "Clearly people are very shocked and revolted by this appalling crime.
"It is a very emotive crime. It is a terrible and sickening crime.
"We need to know the motive - we need to know whether this was a case of mistaken identity."
Ms Fish declined to give any details about the person arrested, except to say they were from Nottinghamshire.
Nottinghamshire Police - who on average dealt with more than one shooting a week in 2003 - made a fresh appeal for help.
They want information about a gold-coloured car, believed to have blacked-out windows, which is thought to have carried the killer.
Officers are also keen to trace members of a 30-strong group of youths who were nearby when Danielle was shot.
Superintendent Dave Colbeck said officers had received intelligence that there could be trouble at the Goose Fair, where the teenager had spent the evening.
But he said that, although measures had been put into place to combat any problems, the information was not specific and no extra patrols were operated in the St Ann's area.
He added that, before Danielle's killing, there had been no shooting-related injuries in Nottingham for four months.
'Enough is enough'
The congregation of Chasewood Baptist Church, where Danielle's family worship, paid tribute to her at their Sunday service.
Reverend Anna Ratcliffe has been comforting the family over the weekend and told BBC Radio Nottingham there is great shock and disbelief in the area and a growing sense that "enough is enough".
Danielle's grandfather, Alvin Beccan, was tearful as he spoke of his "friendly, easy-going" granddaughter, and how his family had been devastated by the drive-by shooting.
Speaking from his terraced home just a few minutes' walk from the scene of the tragedy, he said: "She was just easy-going. She was a nice girl.
"She was popular. All the family are cut up about it."
Danielle was walking home from Nottingham's Goose Fair in the early hours of Saturday just ahead of the shooting.
She died during emergency surgery at the Queen's Medical Centre, Nottingham, of a gunshot wound to her abdomen.
A 20-year-old woman who lives near the crime scene, said: "Those people who did this are not human, they are evil.
"I feel so sorry for her mum and dad as I am a young parent myself."
Friends of Danielle described her as a popular girl who loved music and dancing. Her ambition was to be a beautician.
Carla Browne, 16, said: "I saw her laughing and joking on the dodgem cars only a couple of hours before she was dead.
"She was a really nice girl, not big-headed or one to cause trouble, just out enjoying herself. We are all so upset. It could have been any of us."