Complex sentence: Several men were arrested in connection with the murders in 1969, but acquitted for lack of evidence, which caused popular outrage at the criminal justice system which, at that time, was still based on English law and practice.
Split into simpler sentences: Several men were arrested in connection with the murders in 1969, but acquitted for lack of evidence. This caused popular outrage at the criminal justice system which, at that time, was still based on English law and practice.