The badly-mutilated body of reporter Arsene Salomon Mbani Zogo, known as "Martinez," was found a few days after he was abducted in front of a police station outside the capital Yaounde on January 17 last year.
The 50-year-old ardent anti-corruption and anti-cronyism campaigner had often singled out government officials by name, earning the ire of powerful figures.
Those on trial at Yaounde Military Court include Leopold Maxime Eko Eko, the then-director of Cameroon's powerful military intelligence service, his head of operations Justin Danwe, and members of a military commando accused of Zogo's kidnap, torture and murder.
Jean-Pierre Amougou Belinga, a wealthy businessman believed to be close to ministers and officers in the Central African nation, is also amongst the accused.
All are accused of either actively taking part in or complicity in Zogo's kidnap, torture and murder.
The killing caused an outcry in the country, which has been ruled with an iron fist for more four decades by President Paul Biya, 91.
The defendants showed no signs of any emotion during a three-hour hearing as the charges against them were read out.
The lawyers were then invited to present their initial observations by Colonel Jacques Misse Njone, presiding the session, before he adjourned the case to next month "to respond to all the observations and communicate the lists of witnesses".
Calvin Job, the Zogo family's lawyer, complained that "the civil parties have never been asked to participate in the investigation."
"This is unacceptable. To date, I have not had access to the file," he added.
The court commissioner promised to rectify that and make the file available.
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