A team of doctors had examined the bodies and had concluded that none of the Riddles had been poisoned, stabbed, shot, strangles, suffocated, or (as far as they could tell) harmed at all. - а здесь had examined потому что до того, как полицейские читают отчет? или дело скорее в результате?
И то, и то плюс Present Perfect, улетевший в прошлое.