Most finished serving their sentences of five months in prison earlier this month, and were deported.
Their sentences of seven years in prison followed by 13 years on probation are more than double what prosecutors recommended.
With their appeals exhausted earlier this month, Mr. Marshall and Mr. Morrissey had been scheduled to surrender on Monday and begin serving their sentences of one to three years.
As our colleague Kareem Fahim reported last month, a court upheld their sentences of five years to life in prison for their leadership roles in the protest movement.
Their sentence of nine months' hard labour was suspended but Mandela was banned from attending meetings or talking to more than one individual at a time.
Under the peace accord, those responsible for war crimes who confess are eligible to avoid prison and serve out their sentences of up to eight years with as yet undefined "effective restrictions of liberty".
So, Mr. Morgenthau must decide whether it is preferable to give immunity to a murderer in order to set free two possibly innocent men, or to refuse immunity and let them complete their sentences of 25 years to life.
The three cadets who pleaded guilty to sexual assault have completed their sentences of 10 and 12 months and are now applying for asylum from an immigration detention centre, according to Cambridgeshire police.
Two other doctors did not appeal their sentences of 15 years' imprisonment, instead fleeing the country.
Found guilty of "statutory communism", their sentence of nine months' hard labour was suspended for two years.
