Norfolk police 'puzzled' by RAF Marham attempted kidnap
Police investigating the attempted kidnap of an RAF serviceman said they are "puzzled" by the attackers' motive.
A knife was brandished during the incident near RAF Marham, Norfolk, on 20 July as men tried to drag the victim into a car before they were fought off.
Police said they have had 500 calls from members of the public in relation to the attack.
Det Supt Paul Durham said it could take "several months" to view CCTV footage.
He said: "We're no clearer at the moment to establishing exactly what the motivation was.
"Until we've latched onto something significant through the CCTV or public appeal, we may not be in a position to know."
Det Supt Durham previously said there was "no credible evidence" to suggest it was a terrorist attack.
Investigators are said to be continuing a "painstaking" trawl through CCTV footage from the area.
Det Supt Durham, from the Norfolk and Suffolk Major Investigations Team, said: "It's a great concern in terms that we've still got two suspects outstanding and obviously we're working really, really hard to rectify that.
"In terms of the pace of the investigation, from the very outset it was evident that this was going to a be a slow-pace investigation in terms of the focus around CCTV footage in particular which is fairly sporadic and of varying quality."
One suspect is described as of "Middle Eastern appearance", between 20 and 30 years old, approximately 6ft (1.8m) tall, with a well-groomed beard.
The second man, who is of similar appearance, is slightly younger, about 5ft 10in (1.78m) tall and was clean-shaven with short, dark hair.
The victim was approached by two men while jogging near the base.
He wrestled one man to the ground - possibly leaving him with a black eye - before another man, armed with a knife, tried to attack him.