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.