Nkumba then requested the suspect to go with him to his vehicle so that he could write out a fine for him.
Mohoebi requested the traffic officer's permission to go to his vehicle to collect his phone.
Witnesses said that they heard several gunshots and they saw Mohoebi running back to his Jeep and drive away at high speed.
The police chased the Jeep which was recovered at the Maseru border post where Mohoebi and the two people he was with at the time were arrested.
The three suspects appeared in court several times and the other two were acquitted.
Mohoebi, who has been in custody since his arrest, was charged with a count of murder. He was also charged with robbery with aggravated circumstances, possession of an illegal firearm and possession of ammunition.
He pleaded guilty to all counts.
Prosecutor Eric van der Merwe said although Mohoebi had pleaded guilty, he had not shown any remorse for his actions.
Judge Brian Mashile said the sentencing should serve as a warning to communities that no one was above the law.
Through his legal counsel, Mohoebi apologised to the Nkumba family.
Mpumalanga MEC welcomes life term for man who killed traffic officer
Mpumalanga community safety, security and liaison MEC Pat Ngomane on Monday said a life sentence handed to a man who shot dead an on-duty traffic officer would serve as a deterrent to those who intimidate and assault traffic officers.
Ngomane welcomed the sentence handed to a Lesotho national who murdered a traffic officer in 2016.
The Pretoria High Court sitting in the Delmas Magistrate's Court sentenced Alexander Mohoebi for the murder of Bongani Nkumba.
Nkumba was murdered in Standerton on August 5 2016 while performing his duties.
Nkumba observed a black Jeep vehicle which stopped in a non-stopping area and approached the driver and requested him to produce his driving licence.
He informed the driver, Mohoebi, that he was going to issue him with a fine and also take him for alcohol testing.
Nkumba then requested the suspect to go with him to his vehicle so that he could write out a fine for him.
Mohoebi requested the traffic officer's permission to go to his vehicle to collect his phone.
Witnesses said that they heard several gunshots and they saw Mohoebi running back to his Jeep and drive away at high speed.
The police chased the Jeep which was recovered at the Maseru border post where Mohoebi and the two people he was with at the time were arrested.
The three suspects appeared in court several times and the other two were acquitted.
Mohoebi, who has been in custody since his arrest, was charged with a count of murder. He was also charged with robbery with aggravated circumstances, possession of an illegal firearm and possession of ammunition.
He pleaded guilty to all counts.
Prosecutor Eric van der Merwe said although Mohoebi had pleaded guilty, he had not shown any remorse for his actions.
Judge Brian Mashile said the sentencing should serve as a warning to communities that no one was above the law.
Through his legal counsel, Mohoebi apologised to the Nkumba family.