copyright AFP image caption The only suspect was released on Tuesday, adding urgency to the manhunt

There appears to be evidence that, despite being stabbed, Mr Urban wrestled his hijacker for the steering wheel.

The post-mortem examination suggests that Mr Urban survived up until the attack and was shot dead when the truck came to a halt. No gun has been recovered.

Police say they are acting on hundreds of tips from the public and are examining DNA traces from the cab of the truck.

The IS group claimed the attack through its self-styled news agency, saying it was "in response to calls to target nationals of the coalition countries".

Prosecutor Peter Frank told reporters that the style of attack and the choice of target suggested Islamic extremism.DC United 2, Atlanta United 1 | 2017 MLS Match Recap

The founding MLS club knocked off their expansion counterparts for the second time in two tries on Wednesday, riding a gloriously-struck Patrick Nyarko side volley to a 2-1 win at RFK Stadium.

The two sides traded goals in the midst of a lively first half, both keyed by their opponents' errors. First Atlanta exploited a slack back pass by Ian Harkes to race out on the break, with Julian Gressel finishing firmly at close range. Six minutes later Luciano Acosta intercepted a poor pass by Alec Kann and then compounded the goalkeeper's embarassment by beating him at the near post with a low worm-burner.

The second stanza unfolded in similarly breathless fashion, yet despite many chances, Miguel Almiron and the