The International Press Institute (IPI) today joined international observers in calling on Kenya to conduct a full investigation into the beating death last week of a journalist in an attack that his colleagues said may be linked to reports on a case before the International Criminal Court.

According to local media, journalist John Kituyi, 63, was killed on April 30 in the town of Eldoret, in western Kenya. Kituyi was on his way home from his office when two unidentified assailants on motorcycles attacked him with a blunt object.

He suffered severe injuries to his head and was pronounced dead on his arrival at the Eldoret Hospital. While the journalist’s phone was taken, other valuables including cash and a watch reportedly were not, suggesting that the crime was not a robbery.

Kituyi was a veteran journalist and founder of The Mirror Weekly, mainly covering local news. Recently, the newsmagazine reported on the International Criminal Court (ICC) trial in The Hague against William Ruto, Kenya’s deputy president. Ruto is accused of crimes against humanity, including mass murders, deportations and persecutions that came amid the crisis in 2007 to 2008 that followed Kenya’s disputed Dec. 27, 2007 presidential election.

According to a statement by Kituyi’s brother, those close to the journalist suspect the killing to be linked to his journalistic work.

“We are very concerned by the suggestion that Mr. Kituyi’s reporting on this case may have led to his death, especially given the reported number of instances in which witnesses in the ICC case have been threatened or have disappeared,” IPI Director of Advocacy and Communications Steven M. Ellis said. “We urge Kenyan authorities to conduct a full, swift and transparent investigation into the crime and send a strong signal that such violence will not be met with impunity.”

Several cases of threats and disappearance of witnesses linked to the ICC trial have been reported since an investigation was formally opened in 2010. In December 2014, a defence witness in the ICC trial of Ruto was abducted in Eldoret and later found dead, despite living under an ICC protection scheme.

Numerous journalists have reported being threatened and some said they were attacked in Eldoret, a town that saw a great deal of violence in the post-presidential election crisis.

The incident is the latest troubling development for press freedom in Kenya, where Parliament in 2013 passed two repressive bills in the wake of a terror attack; bills that both carried the potential to restrict the freedom of the press.

Parliament also in December 2014 passed a controversial security law that critics said could hinder the news media. Although Kenya’s High Court overturned some of the restrictions on media reporting imposed by that law, tensions between media and the government remain.