The suicide bomber who blew himself up amid Christmas shoppers in Stockholm a year ago had also rigged a car bomb but failed to set it off with a walkie-talkie, Swedish authorities said Wednesday.
New details from the nearly yearlong investigation showed a series of technical glitches prevented Taimour Abdulwahab from inflicting mass casualties in one of the Swedish capital's busiest commercial areas.
The Iraqi-born Swede only managed to kill himself in the Dec. 11, 2010, attack.
Anders Thornberg, deputy head of the Swedish Security Service, said only some of the explosives Abdulwahab was wearing detonated, apparently because of a problem with the trigger.
An unexploded bomb was found in the burned out wreck of the car he had set on fire about 250 meters (270 yards) from the bomb site, Thornberg said. It was hooked up to a walkie-talkie that the suicide bomber was carrying, but the remote control mechanism failed, Thornberg said.
Abdulwahab may have intended to set off the car bomb as emergency crews arrived to put out the fire, prosecutor Agnetha Hilding Qvarnstrom said.
Surveillance camera video released by police showed Abdulwahab walking back and forth between a busy pedestrian street and a less crowded side street before the bomb exploded. Hilding Qvarnstrom said he may have encountered a problem with the explosives, and tried to fix it when it went off.
"He was carrying about 9 kilos (20 pounds) of explosives on his back and about 4 kilos (9 pounds) of explosives on his stomach," she said.
Only some of the explosives he had strapped to his stomach went off, and none of those he was carrying in a backpack.
Investigators said there are no signs anyone helped Abdulwahab to physically carry out the attack, but they are still investigating whether he got financial or other help. In March, police in Scotland arrested a man suspected of aiding Abdulwahab.
His wife in England was also arrested but later released.
As a child in the early 1990s, Abdulwahab and his family left Iraq for Sweden but he spent much of the past decade in Britain, where he lived with his wife and three young children.
The Swedish investigators confirmed Abdulwahab had traveled to Syria and Iraq in 2007 and 2009 but declined to say whether he had been in contact with or received training from al-Qaida or other terrorist groups.
Before he set the car on fire, Abdulwahab e-mailed a sound file to security police, a Swedish news agency and his family referring to Swedish troops in Afghanistan and a Swedish artist's drawing of the Prophet Muhammad as a dog, which angered Muslims.
Abdulwahab also apologized to his family for misleading them, saying "I never went to the Middle East to work or to make money, I went for jihad."
Terrorism expert Magnus Ranstorp of the Swedish National Defence College said the sophistication of the explosives suggested that Abdulwahab had received training from a terror network.
"He said he went on jihad. He said he acted on behalf of the Islamic state, which is an indirect reference to al-Qaida in Iraq," Ranstorp said. "But there are massive question marks as to his radicalization trajectory, as to his movements and connectivity to potential al-Qaida forces."
Investigators said Abdulwahab traveled from England on Nov. 19, 2010, and stayed with his family in Tranas, Sweden. Qvarnstrom said he left the family home around 11:30 a.m. on the day of the attack, and they expected him back in the afternoon.
Instead he drove 170 miles (270 km) to Stockholm _ police were able to map his journey except for a 40-minute period before he left Tranas, which is when he is believed to have picked up the explosives.
After a 45-minute detour due to entering the wrong address in the car's GPS navigating system, he arrived at his intended destination in the capital at around 4:15 p.m., parked the car and sent the sound file, Hilding Qvarnstrom said.
About a half hour later the car was engulfed in flames, with fireworks, gasoline and liquid gas tanks exploding and sending thick black smoke into the air.
Investigators said Abdulwahab purchased all of the bomb-making ingredients, including chemicals, nails, pellets and screws, at shops in Sweden, except for the metal cylinders that he purchased over the Internet.
"He had the knowledge of how to build a bomb," Thornberg said. "Where he got it, we don't know."