Police have detained the two domestic helps of Ghoraghat Upazila Nirbahi Officer (UNO) Wahida Khanam for interrogation over the attack which left her seriously injured.
Confirming their detention, officer-in-charge of Ghoraghat Police Station Amirul Islam on Monday said Jobeda and Arsona have been kept at the district Detective Branch of police office.
Police picked them up from the respective houses on Sunday night, he said.
Earlier on Saturday, Jobeda was released after interrogation over the attack.
Meanwhile, a Dinajpur court on Sunday placed Asadul Haque, the prime accused in the case filed over the attack on the UNO on a seven-day remand.
Senior Judicial Magistrate Moniruzzaman passed the order after the investigation officer (IO) of the case sought a 10-day remand.
The case has been transferred to the Detective Branch of police for investigation.
Officer-in-charge of district DB Imam Zafar has been made the IO of the case.
Two other accused -- Nabirul Islam adn Santu Kumar -- were placed on a seven-day remand in the case on Saturday.
Rapid Action Battalion which arrested Asadul handed him over to police on Saturday evening as he was under treatment at Rangpur Medical College Hospital.
Others who were arrested over the attack are M Shahjahan Sheikh, Sohel Rana, Asadul's elder brother Ashraful Islam, Sultan and Shyamol Chandra.
Miscreants stormed the official residence of the UNO in the early hours of Thursday and beat her and her father Omar Ali with hammers, leaving them injured.
They were first taken to Sadar Hospital from where Wahida, 35, was shifted to a Rangpur hospital where she was given treatment at its intensive care unit.
The UNO was airlifted to Dhaka and admitted to the National Institute of Neurosciences and Hospital on Thursday.
Her brother filed a case with Ghoraghat Police Station over the attack.