Det Con Benjamin Harris, of Hampshire police, led the investigation into the accusation.
He previously told the inquest the person making the claim had said Donaldson had told them that she would take her own life “if someone finds out” about the allegation.
Harris said he had considered the possibility that Donaldson’s reported comments could be a “form of control” against the complainant.
He said he reported the comments to his senior officers and advised his colleagues, who subsequently arrested Donaldson.
Harris said that after the interview he graded Donaldson’s risk of self-harm as “standard” and said “she had no indication that she wanted to take her own life”.
He added the police did not have the powers to detain someone unless they presented an “imminent” danger to themselves.
A post-mortem examination gave a cause of death of hanging and found Donaldson had non-fatal levels of medication in her blood which were consistent with an overdose, the inquest heard.
Coroner Jason Pegg recorded a conclusion of suicide.