Mexico President Andres Manuel Lopez Obrador on Thursday inaugurated a monument in honor of nine Mormon women and children killed in a massacre last year in the country's north.
Lopez Obrador promised to punish those responsible for the murders as he unveiled a statue paying tribute to the victims in Bavispe in Sonora state.
"This memorial will be a permanent tribute to the victims... We have arrested those responsible for this crime and we're going to keep going until the whole truth is known and justice served," Lopez Obrador told members of the Mormon community present.
The three women and six children from a breakaway Mormon community with dual US-Mexican nationality were on a remote road in a lawless region between the states of Chihuahua and Sonora when gunmen attacked their cars, a crime that sparked outrage on both sides of the border.
The government has arrested 17 people but has more than 15 outstanding arrest warrants and believes more than 40 people took part in the attack.
Authorities believe the attack was the result of a mistake between drug-trafficking groups in the area.
But the killings increased the pressure on the government to show it was doing more to tackle brutal violence by drug cartels.
Mormon families of US origin that settled in the north of Mexico at the end of the 19th century have been critical of Lopez Obrador over the massacre.
There have also been protests in the US while President Donald Trump threatened to designate Mexican drug cartels as terror groups, leading to fears of Washington meddling in Mexican affairs.
Lopez Obrador defended Trump, though, saying he had "always been very respectful of our sovereignty."
Since December 2006 when the Mexican government launched an anti-drug operation, there have been more than 300,000 violent deaths, the majority linked to criminal gangs, according to official figures.