Husband of NSW teacher murdered in Kenya treated as 'prime suspect'

The estranged husband of Australian teacher Gabrielle Maina is being questioned as the prime suspect in her murder, a Kenyan newspaper reports.

The mother of two was shot dead in Nairobi on Thursday.

Ms Maina's husband, Cyrus Bernard Maina Njuguna, and another man, John Njuguna Waithira, were arrested on Monday over the shooting in the exclusive suburb of Karen.

Her lawyer, George King'ori, earlier on Tuesday told AAP the couple was in the midst of divorce proceedings in the Kenyan courts after the 40-year-old had been granted a restraining order against her husband in April.

"She feared he had become irrational," Mr King'Ori told AAP.

Karen police confirmed to Kenya's The Standard that Mr Maina was being held as the prime suspect in Ms Maina's murder.

"We believe he has information that can help us know how and why she was murdered," Karen OCPD Cunningham Suiyanka told the newspaper.

"He is here with another suspect for interrogation by the DCI."

Police are checking Mr Maina's phone.

Investigators also revealed to the newspaper details of the attack on Ms Maina, 40.

It's believed Ms Maina was accosted by three men as she walked home.

After she was shot, the three men took her mobile phone and fled on a motorbike.

She was kneeling at the time of the attack, according to a post-mortem.

Ms Maina moved to Nairobi from Sydney in 2015 so her two sons could experience another culture and grow up near her husband's extended family, a friend told AAP this week.

Before moving to Nairobi, where Ms Maina was head teacher at the elite Hillcrest Preparatory School, she taught English and drama for almost five years at Sarah Redfern High School in Sydney.

Mr King'ori said the mother-of-two may have been on her knees when she was shot.

"It is our hope that Gabrielle's family get justice and know (who) committed the brutal act," Mr King'ori said.

"I have some concerns for the children ... now that she is gone. I don't know what will happen to the quality of life the children were used to."