Abdul Hadi Arwani was shot dead in his car on Tuesday in 2008 . suspected terrorism suspects were drafted in to conduct investigation into terrorism . A 46-year - old suspect has been arrested on suspicion of conspiracy to murder .
Abdul Hadi Arwani was found dead in his car on Tuesday in Wembley . Counter terrorism police were drafted in to lead investigation into death . A 46-year-old man has been arrested on suspicion of conspiracy to murder .