Yasmin Ahmed, held at Delhi airport on Sunday en route from Patna to Afghanistan allegedly to join the Islamic State (IS), had obtained her passport from the Patna regional passport office in 2003.

Investigations by intelligence agencies have revealed that 29-year-old Yasmin, hailing from Sitamarhi district in north Bihar, had visited her ancestral village, Moraul, in May-June this year to renew her passport and to get a fresh passport for her five-year-old son, Mohammad Yusuf.

Yasmin's son was with her when immigration officials at Delhi airport detained her and subsequently handed her over to the Delhi police's special cell for interrogation.

The passport of the mother-son duo had been issued from the Patna regional passport office, an Intelligence Bureau official said.

In her passport (N6920081), Yasmin had mentioned her name as Yasmin Jahid, a resident of Sahganj locality under the jurisdiction of Sultanganj police station in Patna.

She had also stayed in Patna's Lohanipur and Phulwarisharif from 2009 to 2011, investigating officials have revealed.

Though senior police officers of Bihar had earlier claimed that they had not received any official intimation either from any central intelligence agency or from the Union home ministry, additional director-general of police (DGP) (headquarters) Sunil Kumar said on Friday the state police were probing Yasmin's connections on their own.

"Since the matter is already in the public domain, we have also launched investigations.

A Sitamarhi district police team visited her ancestral village to inquire about her family," the DGP said.

He, however, clarified that neither Kerala police nor intelligence officials had contacted them to get Yasmin's details.

An investigating officer, who is not supposed to talk to the media, said Yasmin is computer literate with a good command over English, Hindi and Urdu.

She was married to her cousin, Mohammad Syed Ahmad Hussain, also called Mohammad Rashid alias Chhotu, from neighbouring Humayupur village in 2010. The marriage, however, ended in just two years and she settled in Kerala, where she used to teach English in Peace International School.

She came in contact with Abdul Rashid at the same school. Later, they started living togther.

Rashid is among 21 youths who went missing from Kerala and is suspected to have joined the IS.

Yasmin has a palatial house in Moraul village under Bajpatti block in Sitamarhi district, around 135km north of Patna. However, no one lives there and the house is locked.

Her father, Mohammad Zahid, and two brothers, Mohammad Imran and Mohammad Kasim, stay in Saudi Arabia.

Yasmin, who has been living in Delhi for the past two decades, often visited Saudi Arabia to meet her family members.

She has also lived in Aligarh and Hyderabad.

Her uncle, Mohammad Sabir Ansari, said Yasmin had visited her ancestral home in May-June after five years and stayed there for 15 days before returning to Delhi.

Sabir told intelligence sleuths that Yasmin was religious and offered prayers five times a day.

A graduate from Aligarh Muslim University, Yasmin operates computers and always carries a tablet to remain in constant touch with her acquaintances on social media, he added.