London: Major Nidal Malik Hasan, the US Army psychiatrist accused of killing 13 people in a shooting rampage at a military base in Texas, had been plotting the massacre for weeks, a British newspaper claimed today. According to the Daily Star, Maj Malik Hasan bought a Belgian-made FN 5.7 mm semi-automatic pistol at a gun shop less than 15 miles from Fort Hood military base in September, indicati