DETECTIVES investigating the murder of a Luton teenager believe a trivial argument over a car alarm being triggered could have been the catalyst to the 18-year-old s death.Kenneth Dixon, of Muswell Close, received multiple stab wounds and was found at 9pm last Thursday in the front garden of a house in Eddiwick Avenue, Houghton Regis. He later died at Luton and Dunstable Hospital.Earlier that evening a group of Luton youths, which included the victim, had been drinking in the nearby Harvest Home pub, having parked their purple Vauxhall Nova outside.Another set of youths, from Houghton Regis, were sitting outside the pub and when the Nova s alarm went off there was a verbal exchange between the two groups.The Luton gang eventually left but later the two groups met again and were involved in a number of verbal and physical exchanges near the Harvest Home and Sundon Road.Two cars were seen during the scuffles the purple Nova (E318 ECX) and a red one (H117 DOU). Police, who have launched Operation Copley to hunt down Mr Dixon s killer, are anxious to trace anyone who saw these two cars during the evening.Detectives also need to hear from anyone who saw any of the arguments and fights, who might have been involved on the periphery, or who could have been present but not involved.The garden in Eddiwick Avenue was sealed off last week as police hunted for vital evidence. A full incident room is open and there are 25 officers working on the case.Witnesses can contact Dunstable Police on 01582 473248 or Crimestoppers anonymously on 0800 555111. Det Chief Insp Pete McKay and Det Insp Dave Giles are in charge of the murder inquiry and will speak to witnesses in the strictest confidence if necessary.A number of people have been arrested but all are currently on police bail without charge.