Authorities have been searching for survivors and digging up shallow graves spread around the forest throughout this week while hundreds of people are still listed as missing.
Paul Mackenzie, leader of the Good News International Church, was accused of ordering his followers to starve their children and themselves to death so they could go to heaven before the end of the world, which he predicted to be on April 15.
The taxi driver-turned-preacher was denied bail on Wednesday by a Kenyan court.
Onyancha said one more suspect had also been arrested, bringing the total number of those detained over the deaths to 26.
On Friday, 29 bodies were unearthed, including those of 12 children which were found in one grave.
Kenyan President William Ruto appointed a commission of inquiry into the deaths of more than 100 people believed to have starved themselves to death, while a court ordered that the cult leader remain in prison.
The commission of inquiry will examine whether administrative or intelligence lapses contributed to the deaths.
Presidential spokesman Hussein Mohamed said Ruto had also appointed a task force to review regulations governing religious organisations.
Mackenzie has not commented publicly on the accusations against him nor has he been required to enter a plea to any criminal charge. His lawyer George Kariuki told the press on Tuesday that his client could face “possible terrorism charges”.
Mackenzie appeared in court in the port city of Mombasa on Friday, where prosecutors asked a judge to hold him for an additional 90 days as their investigation continued.
The judge said he would deliver a ruling next Wednesday on the prosecution’s request and ordered that Mackenzie remain in custody until then.
Mackenzie, who was wearing a black and pink jacket and holding his two-year-old daughter during the hearing, told journalists at the court that he and some of his supporters were being refused food in prison.
Prosecutors denied this and his lawyer had told the press on Tuesday that his client was eating.