It's been two months since Burundian authorities detained prominent human rights defender (HRD) Pierre-Claver Mbonimpa. What keeps the 66 year-old HRD at Mpimba central prison, in Bujumbura, is deeply disturbing as in the run up to the next elections in 2015 it sends a message to political activists and human rights defenders that the government may be preparing to take a much more hardline approach to its critics and opponents. The activist attracted police attention days after he took part in a discussion on a local radio station about the reported presence of Burundian soldiers in Eastern Congo. He had simply called for an independent investigation into the matter. Choosing to shoot the messenger rather than look into the issue, the authorities have chosen to investigate the human rights defender instead.

By keeping Mr. Mbonimpa behind bars, the government is telling civil society it has no right to question the government on issues of 'national security'. But at the same time, putting him on trial may eventually lift the lid on a Pandora's box of revelations about cross-border military and para-military activities with their attendant effects on human rights, a situation that leaves the activist's fate hanging in the balance. The case of Pierre-Claver Mbonimpa is a test case for the issue of freedom of expression in Burundi, the rights of human rights defenders and the future of a vibrant civil society in the country.

I recently visited Mbonimpa during my recent field trip to the Great Lakes region. It was an encounter that left me with mixed feelings. True, the internationally respected and honored HRD appears to be in good spirits, despite all this time spent in detention. He is also busier than ever: his presence in Burundi's major prison has meant a lot for many inmates who now have easy access to him whenever they need advice on their personal cases. In what must be a surreal scene for prison officials, at times, the inmates have to line up for an appointment with a man who has dedicated his career to the defence of prisoners' rights.

Despite repeated calls for his provisional release, a court in Bujumbura recently validated his preventive detention and confirmed that the criminal case against him would proceed. As a result of his comments on radio, Mbonimpa faces charges of “threatening state security” and “forgery and use of false documents.” The bone of contention is whether he told the truth when he claimed to have evidence of some youth, affiliated with the ruling party, receiving military training by Burundian armed forces on Congo's soil. Rather than investigate the evidence and examine its credibility, the government's arrest of an activist sounding an alarm on an issue of major public concern and its wild allegations against him is both inappropriate and counterproductive.

I first met Mbonimpa 16 years ago, and have known him to be a vocal critic of government excesses, but one whose work has always been fact-based. He is a role model and a mentor to many human rights defenders in the Great Lakes region. It is worth noting that those irritated by his reports have generally had no choice but to accept the fact that Mbonimpa is a meticulous researcher who never gives in to intimidation.

His passion for human rights and his selfless dedication to the welfare of Burundian society led him, in 2000, to set up the Association for the Protection of Human Rights and Prisoners (APRODH), which has become one of the strongest human rights organisations in the country. Mbonimpa has since then served as the organisation's chair, and has done amazing work promoting prisoners' rights. As a result of his outstanding human rights work, Mbonimpa has earned international recognition, including the 2007 Martin Ennals Award and the 2011 Henry Dunant Award.

That notion that Mbonimpa harboured malicious intentions to harm any person, or even the state, defies common sense. The only possible interpretation of the ongoing judicial harassment against him is that it is a thinly-veiled message to civil society that criticism won't be tolerated and that a line has been drawn as to how far anyone can go in probing government action. In the past few years, Mbonimpa has spoken out vigorously against the increase in extra-judicial killings in his country; and while addressing the media, he often stopped short of accusing the government of direct responsibility for the killings. So I ventured to ask him, “If you didn't cross the line then, why now?” He didn't know either, so he just donned his typical disarming smile, as if telling me to address the question to those who jailed him.

During a recent interview with journalists from Radio France International (RFI) in Paris, the Burundian president, Pierre Nkurunziza, sought to justify the incarceration of Mbonimpa by stressing that “freedom of expression has limits”, before making the all-too-familiar argument that one should let justice take its course. But the problem is that Burundi might still have the same type of “justice” that, in 1998, convicted Mr Nkurunziza himself of treason and sentenced him to death!

In a recent visit to Burundi, United Nations Assistant Secretary-General for Human Rights, Ivan Šimonovic expressed his concern at a recent spate of attacks on opponents of President Nkurunziza, apparently involving the Imbonerakure or youth wing of the ruling party. He said “Special attention must be paid to the full respect for freedom of expression, including for journalists and human rights defenders,” The international community must in turn keep up its pressure on the government of Burundi to ensure that the elections are free and fair. Respect for the right to freedom of expression and the role of human rights defenders will be a key indicator of the govenment of Burundi's commitment to that principle. A first step to delivering on that promise would be the immediate and unconditional release of human rights defender Pierre-Claver Mbonimpa.

* Aloys Habimana is the Protection Coordinator for Africa at Front Line Defenders – The International Foundation for the Protection of Human Rights Defenders.