Two heads and other human remains were left at polling stations in the Mexican border city of Tijuana during elections on Sunday.
According to prosecutors in the state of Baja California, a man hurled a head at one polling station, the voting was interrupted as the police were called.
A man left another head and dismembered human remains inside a wooden box placed next to the ballot boxes at another polling station.
The prosecutors further revealed that more human remains were discovered in bags near a third polling station.
The elections were clouded by a wave of political violence that has killed more than 90 politicians since the start of the election process in September.
This is not the first time Tijuana has witnessed gruesome discoveries of human remains, which previously included mutilated bodies hanging from bridges.
Across Mexico, more than 300,000 people have died in a wave of bloodshed since the government deployed an army to fight drug cartels in 2006.