the riot erupted in february 2012 when supporters of home team al-masry - from the canal city of port said - and cairo 's al-ahly clashed after an egyptian league match between the two clubs .
an appeals court ordered the retrial of 73 defendants last year after rejecting a lower court 's verdict , which sentenced 21 people to death .
the clashes in the port said stadium sparked days of violent protests in which another 16 people were killed in fighting with security forces .