The 49-year-old married father-of-two, who had been Alyn and Deeside AM since 2003, was found dead at his home in Connah's Quay, Flintshire, on Tuesday.
He allegedly was not told about details of the accusations levelled against him but was in a "fragile" state of mind when he was relieved of his duties.
Mrs Sargeant had gone downstairs and found a note on the door of her utility room in her husband's handwriting advising her not to enter but to call the police, Ruthin Coroner's Court heard.
She found him inside on the floor.
Mr Gittins said he will be seeking witness statements at the Welsh Assembly, including First Minister Carwyn Jones.
Décès du skieur français David Poisson lors d'un entraînement — Sports
Victime de lésions cérébrales irréversibles, elle est morte à l'hôpital deux jours plus tard. Cette saison, il visait une nouvelle qualification olympique pour les JO 2018 à Pyeongchang.
"But, as part of my investigation, I must gather evidence to assist me in reaching a conclusion, as when the final inquest hearing takes place I will be required to give consideration to reaching a conclusion of suicide, which would require me to be certain that it was Mr Sargeant's intention to end his life".
The senior coroner said his inquest would be a "full and fair examination of the matters which are relevant" but "will not consider the veracity of the allegations made against Mr Sargeant" nor would he be "looking to Cardiff and the Welsh Assembly or the Labour Party and making adjudications as to who is right or wrong and who can be trusted".
First Minister Jones ordered a inquiry into his former minister's death after being criticised by Sargeant's family and friends about the lack of information given to the sacked minister about his alleged mistakes.
He said: 'May I take this opportunity to express my honest condolences to the family, friends and colleagues of Mr Sargeant and to assure them all that there will be a full and fair examination of the matters which are relevant to my investigation and that I shall not allow the inquest to be a trial by press, politics or personality'.
It is understood that details were withheld to protect the identity of the complainants but Mr Sargeant's family and solicitors say being kept in the dark caused him mental anguish.
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