It comes after the lower part of a severed leg was found on the side of the Stuart Highway near Coolalinga on Tuesday.

Providing an update to media on Thursday morning, Detective Senior Sergeant Paul Morrissey said a 23-year-old man and a 50-year-old woman had been arrested.

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He said police established there had likely been a hit-and-run after the leg of a "dark-skinned human being" was found, and that a suspected vehicle had been identified.

A car that matched the description was spotted by traffic police in Palmerston, with investigators later searching the house it was parked at and arresting the 23-year-old resident.

Following further inquiries, police went to a residence in Winnellie and arrested a 50-year-old woman before attending a residence in the Darwin rural area where the body of a "deceased Aboriginal female" was found.

"It will be alleged the 23-year-old male was the driver," Detective Senior Sergeant Morrissey said.

"It will be further alleged the 50-year-old female assisted him in moving the deceased to another location in an attempt to conceal the crime."

An autopsy on the suspected victim will be conducted today.

He said police believe they have identified the victim and have been in touch with her family. However, further forensic testing is being done to confirm her identity.

Detective Senior Sergeant Morrissey said failing to stop and render assistance or attempt to hide a hit and run accident will "just turn into more trouble and pain for all parties involved."

It is believed the alleged offenders were driving at speed at the time of the incident.

The man and woman remain in custody and are expected to be charged later today.

The woman is the 11th pedestrian to die on NT roads in the past 18 months.

All were Indigenous and six involved hit and run incidents, according to NT police.

Australian Associated Press

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