Two men wearing hoods were lying in wait outside Mohlala's home in Nelspruit when he was gunned down. His son was also shot but survived.
Mohlala, a former vice president of the South African Football Association, headed the local council of Mbombela, where the stadium is being built in Nelspruit for the World Cup.
He made headlines a year ago when he claimed that construction contracts for the 46,000-seat Mbombela Stadium had been manipulated.
His outspokenness reportedly led to some members of the ruling African National Congress (ANC) wanting him ousted. A report into the allegations against Mbombela municipal manager Jacob Dladla was allegedly covered by ANC allegations.