The man, a migrant labourer hailing from Dera village under Rajnagar police station area, was detained by the police on Wednesday. He had set ablaze the house on Tuesday night.
"He might have hatched the plan to settle the score with in-laws because his wife had left him in dire straits at a time he needed care and warmth," an official said.
His wife had deserted him and left for his parental house along with two children after he tested HIV positive.
"We are treating the case from a humanitarian angle because the culprit is an HIV/AIDS patient. Despite the alleged offence, we are yet to put him under arrest. Attempt is being made to unite the estranged couple," he said.
As misconception and ill-conceived notion about the disease reigns supreme mostly in rural areas of the district, many are still scared of getting branded as AIDS patients.