The four main suspects detained after the terrorist attack on a concert hall in Moscow were brought to the Russian capital for questioning on Saturday evening, according to state news agency TASS. According to Russian authorities, the four men were arrested in the Bryansk region to the south-west of Moscow which borders Ukraine and Belarus. They have now been driven in a heavily secured motorcade to Moscow to face the so-called Investigative Committee. An application for an arrest warrant is to be made in court in the coming days, TASS reported. All of them face life imprisonment, according to…