Before announcing the suspects, Moreno-Ocam­po met with Kenyans including investigators and lawyers at the Serena Hotel in Nairobi. The lawyers approved of his desire to combat impunity and prevent political violence during the next election in Kenya. But they warned him that Kenya wasn’t Sudan or Congo. Its politicians were just as ruthless but more sophisticated. The suspects would try to kill the cases and discredit the I.C.C. So would President Kibaki’s government. Kenyatta, elevated to deputy prime minister after the postelection violence, was his protégé. “They’re going to fight back very, very hard,” James Gondi, a Kenyan lawyer who had interned at the I.C.C., told Moreno-Ocampo. But the prosecutor seemed unconcerned. He pointed out that he’d put away generals in Argentina.

Later, some questioned whether Kenyatta was as culpable as the case against him claimed. George Kegoro, the Waki Commission secretary, told me that when Kenyatta was questioned by the commission, he “saw himself as a peace­maker.” Pascal Kambale, the Waki commissioner, said that “irrespective of Kenyatta’s involvement, Mungiki was going to do what they did.”

In the I.C.C. system at the time, the prosecutor’s office collected enough evidence for the court to hold pretrial hearings, in which the judges would decide whether there were sufficient grounds to confirm the charges. If they did, the cases proceeded. This gave defendants ample time to destroy evidence and interfere with witnesses, a recurring problem.

By the time Moreno-Ocampo’s team got moving in Kenya, more than two years had elapsed since the postelection violence. Their investigation, which would go on for over four years, was far more rigorous than those in Congo or Sudan. They interviewed hundreds of victims and suspected perpetrators. But many witnesses who had opened up to the Kenyan commissions were no longer willing to speak.

Faced with a dwindling pool of evidence, Moreno-Ocampo’s team approached General Ali’s attorney with a possible offer: If Ali testified against Kenyatta and Muthaura, the charges against him might be dismissed. The Kenyan commissions had gathered strong evidence against Ali, but circumstances had changed. The attorney general had forbidden the police to speak to the I.C.C. According to Kenyan investigators with whom I spoke, other police officers who were involved in the violence had been killed. Ali turned down the offer. The judges didn’t confirm the charges against him. The prosecutor’s office later withdrew the cases against Muthaura and Odinga’s party chairman.

There was one group willing to help the court: Mungiki. Many gang members were gone — “killed or forcibly disappeared in an apparent cleanup operation,” the prosecution claimed — but some were still alive and willing to testify. Especially crucial were three confidential Mungiki “linkage” witnesses. One claimed he saw Kenyatta at meetings where attacks were planned; another, that he was told of these meetings, though he wasn’t present; and a third, that he met with Kenyatta beforehand to discuss violence.

The case hinged on these men. But some people in the prosecutor’s office worried about their reliability. Kenyatta’s attorney claimed in court that the first two witnesses tried to extort him in exchange for information that could aid the defense, and when he refused, threatened him. He showed little evidence of the claim, but neither did the prosecution dispute it. (“It strikes me as entirely plausible,” Benjamin Gumpert, an I.C.C. lawyer who worked on the Kenyatta case, told me.) Kenyans who knew the third witness, meanwhile, not only doubted his account but also questioned whether he was in Mungiki. Maina Njenga’s former lieutenant says the witness was never in the gang. There were arguments in The Hague over whether to use him. The former court attorney told me it appeared the man would say anything to get into the court’s protection program. But the case against Kenyatta was too thin to sacrifice him.