The call was made during questions tabled in Parliament, which revealed the average time between a fatality and the start of a prosecution has risen to 879 days, in the last five years.
Questions by the MP also revealed that, since 2005, the average time between a fatal accident and a a decision to prosecution being approved was 751 days.
Thirty per cent of cases did not reach prosecution stage until betweenthree to four years after a worker’s death.
Mr Hepburn said: “These figures reveal there is something terribly wrong in how we are dealing with workplace accidents.
“From an already poor base we have seen a serious decline in conviction rates and an increase in the length of time before a prosecution even begins. This is causing human misery and the Government must not turn a blind eye to these failures.”
Brian Rye, acting general secretary of construction, the Union of Construction, Allied Trades and Technicians (UCATT), said: “The length of time between a fatal accident and a prosecution is far too long. Justice needs to be done but it must be done more quickly.
“The families who have lost a loved one should not have their lives put on hold for so long.”