Three people among them the wife of a gunman who kidnapped Italian aid worker Silvia Romano appeared in a Malindi court on Tuesday.
Rukia Nuno, who has a two-week-old infant, Dumal Haji Osman and Hassan Borow Khamis were, however, not charged.
Police sought 30 more days to hold the suspects so as to complete investigations.
The suspects are facing a charge of aiding the commission of a terror act.
Malindi Chief Magistrate Julie Oseko allowed the suspects to be detained by police for 20 days then charged.
She said the time is enough for the Directorate of Criminal investigations to conclude the probe.
Investigating officer Chief Inspector Peter Muriithi told the court the suspects were arrested after the kidnap on November 20.
Five people were injured during the attack at Chakama village.
"This is a matter of public interest, the information released is sensitive to national security," he said.
Muriithi said they could not complete investigations within 24 hours due to the technicalities involved.
Osman and Khamis were arrested by police on Saturday at Asa, a remote village in Garsen constituency.
Police said the village is deep in the forest where a major multi-agency operation is underway to rescue the aid worker.
Nuno, who is breastfeeding, was arrested at Tarasaa in Garsen last week after police intercepted her phone conversation with her husband.
Security forces recovered a Toyota Fielder in the forest. They said forensic experts will examine it.
Investigators said they have extended the search for Romano to Mombasa, Kilifi, Garrisa, Tana River and Somalia.
They believe the abductors are trying to cross into Somalia with the aid worker.
Security officials are using drones to track the abductor's movement.
Magistrate Oseko ordered police to hold the suspects until December 14 when the case will come for up for mention.
