A mourner kneels beside candles near the entrance tunnel of the Love Parade in Duisburg, Germany, where 20 people died in a crush of people. (Mario Vedder/Associated Press)German prosecutors are investigating whether negligent manslaughter was involved in the deaths of 20 people killed in a crush at the Love Parade techno festival.

But amid a clamour of questions about who is to blame, they said Monday they haven't yet identified any suspects.

The tragedy Saturday — near a tunnel that was the only entrance to the festival grounds in the western industrial city of Duisburg — injured 511 other people.

Police raised the death toll late Monday to 20 from 19 after a 21-year-old German woman succumbed to her injuries in a hospital.

It remains unclear what triggered the panic, but it appears that people trying to escape the surging crowd climbed up a metal stairway in front of the tunnel and then fell into the crowd and were trampled or crushed.

"The investigations are concentrating on the allegation of negligent manslaughter and negligent bodily harm," said Rolf Haferkamp, a spokesman for Duisburg prosecutors. "They are not directed against any concrete person at present."

A union representing German police blamed organizers and officials in Duisburg. But witnesses pointed the finger at police and private security staff, saying the panic broke out after they closed one end of a tunnel — the only entrance — when the festival grounds became too full.

Police denied this and said they actually opened a second exit to disperse the masses before the accident happened.

At a news conference Sunday, Duisburg officials, police and the organizers provided few answers, frequently deflecting questions by noting that an investigation is underway.

The Tageszeitung newspaper's sarcastic front-page headline summed up many Germans' reaction to that: "19 Dead — No One Was to Blame." Berlin's B.Z. tabloid ran a picture of the officials under the headline "Parade of Failures."

Crowd estimated at 1.4 million

One key question is whether the venue, an old freight railway station that local media estimated could handle 300,000 people, was suitable for the event. German media reported that up to 1.4 million people showed up, although police suggested the figure was likely far lower, given that the national railway brought 105,000 people to Duisburg in the preceding hours. Since the event was free, the number who attended may never be known.

Der Spiegel magazine reported Monday that the city had sent a letter to organizers limiting the number of people at the grounds to 250,000. Haferkamp, the prosecutors' spokesman, didn't confirm that.

"The area was not large enough right from the start, that's what I think," Duisburg resident Kurt Moczko said. "I just can't imagine how this area should be sufficient for 1.4 million people."

Carsten Schroeter, another Duisburg resident, echoed that sentiment. "I think it is not right to simply blame the police because I think the planning ahead of the event should have been different," he said.

The Love Parade was once a Berlin institution, but was held for the last time in the capital in 2006 after financial problems and tensions with city officials over cleanup costs.

It started rotating among cities of the Ruhr industrial region in 2007, though last year's designated host, Bochum — a smaller city than Duisburg — cancelled it over concerns that it lacked the infrastructure to cope.

Organizers said Sunday that the Love Parade would never be held again.