Ten people in the cotton-growing town of Fana have been decapitated since 2018, sparking fears of ritual killings.
"We have arrested the main suspect," local prosecutor Boubacar Moussa Diarra told AFP by phone.
He is a 42-year-old unemployed Malian man with no fixed address, he said.
"The details he gave of the crimes correspond to the nature of the murders," he said.
A police official who declined to be named revealed the suspect had been arrested a year ago but had only confessed last week to the grisly murders.
Neither the prosecutor nor the police official revealed the possible motive for the crimes.
The victims included a former soldier, a housewife, a five-year-old albino child and a two-year-old girl, and had apparently nothing in common.
In most cases, their heads were found, but their blood had been collected, sparking fears of ritual murders and demands for a local police station that were met in 2019.
The local authorities have urged caution regarding theories surrounding the killings and stress that the investigation is continuing.
Mali Makes Beheadings Probe Gains
FILE: in the city of Makalondi, southwestern Niger, in the middle of the 'three borders' (Niger-Mali-Burkina) zone, the scene since 2017 of bloody attacks attributed to Islamic State in the Greater Sahara (ETGS). Taken 6.3.2022
Investigations into a string of beheadings in southern Mali that have shocked the Sahel nation have scored a breakthrough, judicial and police sources said on Monday.
BAMAKO —