Why is this case being tried in a military court?

Civilians accused of having murdered the Italian ambassador to the Democratic Republic of Congo, his driver, and an Italian police officer in 2021, have objected to trial in a military court. According to this account:

Lawyer Joseph Amzati argued on Wednesday that the military court lacked the jurisdiction to try the defendants because they are civilians.

But prosecutor Lieutenant-Colonel Joseph Malikidogo said a military tribunal was appropriate because the accused had allegedly used "weapons and munitions of war" in the attack.

He added that releasing the defendants would be scandalous because of the "indescribable gravity" of their alleged crimes.

Human rights principles strongly disfavor the trial of civilians by military courts.