Silvia Kimunto Kamau, a Form Two student, was arrested in Juja Town in Kiambu County on May 4, a Nairobi court was told Wednesday.
"She disappeared from school in June 2014 and resurfaced earlier this year, and, after resurfacing insisted to be taken to a Muslim school," prosecutor Duncan Ondimu said.
Mr Ondimu said that intelligence reports showed that she had been radicalised after joining the terror organisation.
"She sneaked back into the country to cause the killings of innocent souls and her associates are at large," the prosecutor added.
As a reply to the prosecution’s request for extended detention, the suspect denied ever travelling to Somalia.
"I don't want to be detained because I have never been to Somalia. I have only been in a school in Sigona where they teach about Islam,' she said.
While granting a 10-day extended detention order as sought by the prosecution, the court directed that special regard be accorded to the suspect who is considered a minor.
In the same court, the anti-terrorism police also paraded a manager of a real estate company said to be involved in funding terror activities.
Ms Damaris Wanjiru Njenga of Bemwa Realtors Limited will be detained for 10 days in police custody.
The prosecution said the woman has been in constant communication with known Al-Shabaab members and she may help in the recovery of crucial transaction records.
The two suspects are expected back in court on May 15 for further directions.
