Officials in Peru believe the gun used to fatally shoot revered shaman Olivia Arevalo last week has been found and that it matches the weapon bought by the Vancouver Island man who was killed in retaliation for her death.

Peru's office of the public prosecutor made the announcement in a tweet Thursday that included a photograph of the weapon, a 9-mm Taurus pistol.

Sebastian Woodroffe of the Comox Valley on Vancouver Island was killed in a remote area of Peru on April 19 in retaliation for the shooting death of an 81-year-old Indigenous medicine woman, authorities say. (Sebastian Woodroffe/CBC)

Sebastian Woodroffe, 41, was killed on April 19 in the Ucayali Region of eastern Peru. A 90-second cellphone video of his lynching shows two men dragging the Comox Valley resident by a noose as others looked on. His body was later found buried nearby.

Authorities say they found a document showing that Woodroffe bought a gun on April 3 from a police officer, according to Ricardo Jimenez, head of public prosecutors in Ucayali.

Traditional healer and elder Olivia Arevalo, 81, of the Shipibo-Conibo Indigenous people of Peru was shot and killed at her home last weekend. (Temple of the Way of Light/YouTube)

Jiminez also said a witness testified that a silver-coloured pistol fell from a backpack Woodroffe was carrying as locals of the remote Amazonian village grabbed him before the lynching.

Woodroffe had been Arevalo's patient, and her family believes he killed the 81-year-old because she refused to conduct a ritual in which the hallucinogenic plant brew ayahuasca is used for healing and spiritual growth, said Jimenez.

<a href="https://twitter.com/hashtag/Fiscal%C3%ADaInforma?src=hash&ref_src=twsrc%5Etfw">#FiscalíaInforma</a> <br>2º Fiscalía Provincial Penal Corporativa de Yarinacocha informó que arma con que habrían asesinado a Olivia Arévalo fue encontrada esta madrugada y correspondería a la misma que compró el ciudadano canadiense Sebastian Paul Wooldrooffe el pasado 3 de abril. <a href="https://t.co/hhaAUY94CV">pic.twitter.com/hhaAUY94CV</a> —@FiscaliaPeru

On Monday a Peruvian judge ordered the arrests of two men accused of carrying out the lynching.

Woodroffe moved to Ucayali after raising money so he could learn more about plant medicine in Peru and become an addictions counsellor, according to the crowdfunding website Indiegogo.com, where he listed his plan to spend $6,800 at a Shipibo healing centre.

Ayahuasca has long been used by tribes in spiritual rituals and has fuelled a surge in Amazonian tourism in the past decade as its reputation for treating addiction and trauma and providing spiritual insights has grown.