A 25-year-old man has been arrested after a rancid stench led police to discover he had been living with his dead mother's rotting corpse.

Christopher Aguilar went about his daily routine as his mother, 47-year-old Carmelita, lay dead in a bathtub inside their apartment in Tucson, Arizona.

He has been charged with one count of abandoning and concealing a body, reports KGUN9-TV.

Arrested: Christopher Aguilar, pictured, went about his daily routine as his mother, 47-year-old Carmelita, lay dead in a bathtub inside their apartment

It is not yet known how long the woman had been dead for but her body was do badly decomposed investigators initially could not determine the gender.

The grim discovery was made when neighbours raised the alarm after they grew concerned over not seeing Mrs Aguilar for some time.

'The person was found in a bathtub, I believe, and may have either been bound or was found in some circumstance for police to believe she may not have died naturally,' Dr Gregory Hess, Pima County's Chief Medical Examiner, told KGUN9-TV.

Detectives are treating the discovery as a homicide, but are still investigating whether Aguilar was involved in his mother's death.

'It's one unusual circumstance that piques our interest and causes us to look a little more into this incident,' Sgt. Maria Hawke, told KGUN9-TV.

'We're going to examine any evidence that may be present at the scene where the body is found or the potential scene where a person may have been killed,' Hawke added.

The mother and son's neighbour Gilbert Vidal told the tv station that he saw Aguilar and his mother arguing a few times.

'He was an alright guy but I didn't really trust him because of the look in his eyes, his face, he started looking like he was going nuts,' Mr Vidal said, reportsKGUN9-TV.

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