A few days before the Kano attack, Wazobia FM aired a programme in which presenters talked about how one of the station's journalists had been attacked by local officials and had his equipment confiscated after coming upon a man who refused to allow his children to be vaccinated. They discussed fears people have about the vaccine.
Ibrahim Idris, Kano state police commissioner, ordered the journalists be arrested immediately after Friday's attack. On Tuesday two journalists remained held by police, while the other had been released on bail, police said.
Initially, Idris said the journalists would face charges of "culpable homicide" over the polio workers' deaths. Those charges can carry the death penalty. However, at an arraignment hearing Tuesday afternoon, prosecutors brought lesser charges against the journalists that included conspiracy, inciting a disturbance and obstruction of a public servant. Magistrate Ibrahim Bello ordered a follow-up hearing on Thursday.
Sanusi Bello Kankarofi, manager of the Wazobia FM station in Kano, could not be reached for comment on Tuesday.
There have long been suspicions about the polio vaccine in northern Nigeria, with people believing the drops would sterilise young girls. In 2003 a Kano doctor heading the Supreme Council for Shariah in Nigeria said the vaccines were "corrupted and tainted by evildoers from America and their western allies".
That led to hundreds of new infections in children across the north, where beggars on locally made wooden skateboards drag their withered legs back and forth in traffic, begging for alms. The 2003 disease outbreak in Nigeria eventually spread throughout the world, even causing infections in Indonesia.
Nigeria is one of only three countries where polio remains endemic, the others being Afghanistan and Pakistan.
Nigeria came out of a long period of military rule in 1999 and has an unbridled free press, but journalists are often harassed by police and the State Security Service, the nation's secret police.
Local journalists also have been attacked and killed in the oil-rich nation over their reporting in the past. Last year alone, two journalists in Nigeria were killed. Eighteen journalists have been killed in Nigeria since 1992, according to the Committee to Protect Journalists.
Newspapers and radio stations also often hold off paying journalists their salaries for months at a time. That forces reporters to make money from selling advertising to those they cover or through collecting so-called "brown envelope" bribes slipped into briefing materials at news conferences.
Mohamed Keita, an official with the Committee to Protect Journalists in New York, said his organisation continued to investigate the circumstances surrounding the journalists' prosecution.
"We are troubled by the detentions of journalists insofar as there appears to be no evidence linking their programme to the murderous attacks on the polio clinics," Keita said. "We call on Nigerian authorities to afford the journalists due process under the law."