Complex sentence: Nick Spanos and Stephen Melrose were Australian tourists shot dead in the Netherlands by the Provisional Irish Republican Army on 27 May 1990, which claimed to have mistaken them for off-duty British soldiers.
Split into simpler sentences: Nick Spanos and Stephen Melrose were Australian tourists shot dead in the Netherlands by the Provisional IRA (IRA) on 27 May 1990. The IRA claimed to have mistaken them for off-duty British soldiers.