<p><br /> Swedish authorities say the failed bombing in Stockholm appeared to be "well-planned" and they suspect more than one person was involved in the botched attack.<br /> </p><p><br /> Taimour Abdulwahab al-Abdaly killed himself and wounded two people when he targetted the Swedish capital on Saturday afternoon.<br /> </p><p><br /> Police are now minutely examining material left by the 28-year-old for clues about his accomplices.<br /> </p><p><br /> An audio message emailed to police and Swedish news agency before the attack is being listened to. There is speculation among counter-terrorism experts that a cough on the recording may be from another person.<br /> </p><p><br /> Jihadist websites were filled with tributes to the bomber, including poems and epitaphs describing him as a "hero martyr".<br /> </p><p><br /> Swedish officials said on Monday Abdulwahab apparently carried out his mission alone but had backing from others.<br /> </p><p><br /> Chief public prosecutor Tomas Lindstrand said: "We know from previous experience that this type of crime usually involves more than one individual.<br /> </p><p><br /> "The attack appears to have been well-planned, and we assume that the suicide bomber had accomplices."<br /> </p><p><br /> Officers have also cordoned off Abdaly's family home in Luton where he was living with his wife and three children.<br /> </p><p><br /> Swedish investigators said he visited his family in Tranas, where his father was celebrating his birthday.<br /> </p><p><br /> But on Saturday he loaded his white Audi with gas canisters and travelled to Stockholm to wreak carnage on streets packed with Christmas shoppers.<br /> </p><p><br /> Evidence from the scene indicated that the car failed to explode and al-Abdaly was killed about 300 yards away when explosives strapped to his chest detonated.<br /> </p>