Anders Behring Breivik planned to inject poison into ammunition before launching his murderous assaults in Norway, British press reported Tuesday.
Norwegian authorities have not confirmed that the 32-year-old man behind Norway's worst post-World War II atrocity carried out the threat. At least 76 people died in Friday's attacks.
In a chilling 1,500-page manifesto emailed to recipients across Europe before the attack, Breivik mentioned his intent to inject lethal doses of liquid nicotine into bullets ensuring that every shot delivered a deadly blow, U.K.'s Daily Mail reported.
"I’ve now ordered 50ml — 99 percent pure liquid nicotine from a Chinese online supplier," Breivik wrote in his manifesto last year, the Mail reported. It included, "3-4 drops will be injected in hollow point rifle bullets, which will effectively turn it into a lethal chemical weapon."
Police believe Breivik acted alone when he set off a massive bomb in central Oslo and then hours later massacred 68 others on a nearby island, where up to 600 people — mostly teens —had gathered for a summer political camp. Authorities have not completely ruled out that he had accomplices.
Breivik emailed his manifesto to 1,300 people less than 90 minutes before detonating the bomb in Oslo, The Guardian reported. Breivik told authorities he didn't expect to make it out of alive from the city's center and believed he would have died before carrying out his murderous plot.
Breivik donned a police uniform as part of a ruse to draw young campers to him, appeared in total control during the island rampage, police official Odd Reidar Humlegaard said.
"He's been merciless," Humlegaard said.
Authorities say that in the island attack Breivik used two weapons — a pistol and an assault rifle both bought legally, according to his manifesto.
On the gun application, Breivik had claimed he wanted a rifle to hunt deer. "It would have been tempting to just write the truth; "executing category A and B cultural Marxists/multiculturalist traitors," just to see their reaction,'" according to his diary entry at the same time of his permit application.
The ammunition used was illegal "dum-dum"-style bullets designed to disintegrate inside the body and cause maximum internal damage, a doctor treating shooting victims confirmed to Reuters.
"We still have to find out whether he did use the nicotine, and toxicology tests on the victims will give us the answer," a police official told the Daily Mail. "But his planning appears so meticulous that we fear he may have used the chemicals in this way. We would not put anything past this man."
Many of the Utoya victims suffered injuries consistent with hollow-point expanding ammunition, The Daily Mail reported.
If convicted, Breivik faces 21 years in prison for the terrorism charges. He told authorities he expected to remain in prison indefinitely. A judge ordered he be held for eight weeks, including four in isolation.
Reuters contributed to this report.