Halima's father freedom fighter Helal Uddin Akond made the claim at a press conference in Mymensingh on Monday.
On Apr 2, 25-year-old Halima Khatun set herself on fire inside Gouripur Police Station in Mymensingh, where she used to work.
Her colleagues took her to the Mymensingh Medical College Hospital but she succumbed to burns while being transferred to Dhaka.
SI Mizan is currently behind the bars following a court order.
Gouripur police OC Delwar Hossain refused to accept a formal complaint from Halima, Helal said at the press briefing.
He showed reporters two pages from Halima's diary and a copy of the general diary that he claimed was rejected.
"Halima would have been alive today if OC Delwar took proper actions following her GD," he added.
OC Delwar, however, denies the claim.
"Mizanul told me that Halima verbally assaulted him, a claim that Halima denied. Since now a case is on, we will soon get to know the facts," he told bdnews24.com.
Mymensingh DB police OC Imarot Hossain Gazi, who is in-charge of investigating the case, said: "The evidences have been collected and sent to Dhaka for medical examination."