When she resurfaced in Africa a few years later, she was no longer the penitent widow apologizing for her late husband's mass murder.
She was, instead, a jihadi in her own right, committed to waging war against the West.
She would not be seen in public, or grant interviews, but Kenyan police — and her own writings — describe a woman willing to die for her cause.
In July 2010, a white woman calling herself Asmaa Shahidah Bint-Andrews registered at the exclusive eight-room Genesis birth clinic in the well-to-do Saxonwold suburb just outside Johannesburg. She paid her deposit in cash — 27,500 South African rands, about $3,700 at the time.
She did not want to give birth in a regular hospital, with its impersonal wards, but chose instead a more expensive water birth. She picked the Sage room, which featured a marble birthing pool, leather chairs, and a private bathroom, recalled unit manager Tamzin Ingram.
A baby girl, Surajah, was born with no complications, aided by midwife Lesley Rose, and was duly registered with authorities.
Asmaa Shahidah Bint-Andrews turned out to be Samantha Lewthwaite using an alias. The infant was her fourth child — she had remarried.
Authorities later said she is believed to have entered the country using a South African passport issued to Natalie Webb.
Nearly two years later, in early 2012, Kenyan counter-terrorism police made the startling announcement that Lewthwaite had linked up with key figures in the shadowy al-Shabab terrorist networks, which has ties to al-Qaida and is branded a global threat by U.S. officials. Police said she and others had entered Kenya the year before to plan a bomb attack on a coastal resort over the Christmas holidays.
Police had nearly nabbed her in a raid on Dec. 20, 2011 — just days before the planned attack— but let her go after being fooled by the South African passport she was carrying.