In 1998, during an expedition by Johan Reinhard and Antonio Chávez into the crater, approximately 100 meters below the summit, two collective graves were discovered. The burials were surrounded by stone circles and filled with rich ritual offerings. Alongside the interments, researchers found 47 metal figurines (made of gold, silver, and copper), Spondylus shells, ceramic and wooden vessels, as well as bone and stone artifacts. Due to the extremely harsh conditions inside the crater — high temperatures caused by volcanic activity and acidic soils — the human remains and textiles had undergone significant degradation. The researchers decided to extract the bodies encased in frozen blocks of soil, which were then transferred to the Museo Santuarios Andinos in Arequipa, where they were subjected to bioarchaeological analysis in 2018 by Dr. Dagmara Socha.

Analysis of the remains from Misti revealed that at least eight individuals were sacrificed there. The studies showed that one of the burials contained the remains of male children, and the other of female children; however, a probable determination of sex was only possible thanks to the grave goods, due to the young age of the individuals. The estimated age of the victims ranged from 6 to 13 years. A deformation of the femur in the individual known as Misti 1 may have been linked to his role within the belief system. The deformation must have occurred in early childhood or was congenital. According to some Spanish chronicles, individuals struck by lightning or born with genetic disorder were chosen to serve as priests of the god Illapa.

Two burial sites were located on the Ampato volcano at elevations of 5,800 m and 6,300 m above sea level. The degree of preservation of organic remains varied, due to the different natural conditions prevailing at these two locations. The summit of Ampato (6,288 m asl) was covered by a thick ice cap. Eruptions of the neighboring Sabancaya volcano in 1990-1991 caused the melting of the ice cap, which in turn prompted archaeologists to undertake an expedition. The name Ampato itself comes from the Quechua word hampattu, meaning "toad." Both toads and frogs were associated in Andean folklore with rain and magic. In the Inca Empire, mountain summits were identified with deities responsible for rain. Many local rivers in the Arequipa region originate from mountain glaciers.hampattu” i oznacza ropuchę. Zarówno ropuchy jak i żaby były kojarzone w folklorze andyjskim z deszczem i czarami. W Imperium Inków szczyty górskie były utożsamiane z bóstwami odpowiedzialnymi za deszcz. Wiele lokalnych rzek w rejonie Arequipy zaczyna swój bieg od górskich lodowców.

The mummy known as the Lady of Ampato was discovered during an expedition organized by Johan Reinhard together with the Peruvian guide Miguel Zarate in September 1995. While climbing to the summit, archaeologists found the mummy on the slope. Her tomb was located several hundred meters above, at an elevation of 6,300 meters above sea level. The tomb was destroyed, and its contents slid down the slope. In addition to the mummy itself, archaeologists also found figurines made of gold, silver, and Spondylus shells, remains of llama bones, small bags of corn, and broken fragments of vessels. These items were likely grave goods that slid down along with the mummy. Due to the conditions at the summit, the body underwent natural mummification through freezing. Thanks to CT scans conducted in 2022, it was possible to reconstruct the health condition of the girl and the taphonomic processes. The mummy belonged to a girl who died at approximately 14–15 years of age.

On the plateau at an altitude of 5,800 meters above sea level, archaeologists discovered another ceremonial site where the Incas sacrificed three children. Two of the burials were destroyed by lightning strikes. The children’s ages were estimated to be between approximately 6 and 10 years old.

The name of the volcano comes from the Quechua language and means “peak.” The double use of the word emphasizes that the volcano has several summits. At the top, the Incas built an oval platform with a ramp. Johan Reinhard and José Antonio Chávez led five expeditions to Pichu Pichu between 1989 and 1996. Excavations on the main platform took place in 1996. A collapsed ramp led to the platform. During the excavations, archaeologists discovered two burials: a girl approximately 6 years old and a boy about 3.5 years old.

During the excavations, archaeologists also discovered a sacrifice that included a silver figurine and an uncu (tunic) decorated with silver discs.

Due to the conditions at the summit of Pichu Pichu, no organic remains have been preserved. The girl was buried in a seated position with her legs drawn close to her chest. A gold tube was found on her forehead, which may have been part of a headdress whose organic components had decomposed. During the cleaning of the skeleton, two silver and one gold tupu pins were discovered. A line related to enamel hypoplasia was visible on her teeth. This type of dental growth disturbance is associated with stress caused by malnutrition or culturally induced factors during tooth enamel formation.

Her skull was intentionally deformed. This cultural practice involved deliberately shaping the skull of an infant while the bones were still soft and malleable. The process typically began a few days after birth and continued for several months or even years until the skull achieved the desired shape. The deformation was achieved by binding the head with bands or wraps, or by applying special wooden boards that exerted constant pressure from the sides, top, or back of the head. The purpose of this practice was not only to give the head a specific shape—often elongated or flattened—but also to express cultural identity, social status, or belonging to a particular group. Such cranial deformations were common in many ancient cultures, including Andean peoples.