Why was Jugurtha executed after Gaius Marius celebrated his triumph in 104 BCE?

Following his capture by Lucius Cornelius Sulla in 105 BCE, Jugurtha was brought to Rome as a prisoner of war. His execution in 104 BCE, which occurred at the start of the year in which Gaius Marius celebrated his triumph, was a standard Roman practice for defeated enemy leaders.

In the context of the Roman Republic, the celebration of a triumph served as a public display of victory and restored morale. It was customary for the captured leader of the defeated forces to be paraded through the city during this procession and subsequently executed, often in the Tullianum prison, as a final act of Roman dominance over their adversaries.12