In the case of the 43 missing students in Mexico, the former Mexican Attorney General has been arrested.
The police have executed an arrest warrant against the former top investigator, the Attorney General announced on Friday.
Jesús Murillo Karam was responsible for the initial investigation into the case in 2014.
Only on Thursday did a truth commission accuse the authorities of having falsified evidence to cover up the truth.
The Truth Commission had also declared the students dead and called the case a "state crime."
Murillo Karam is accused of enforced disappearances, torture and offenses against the administration of justice, the statement said.
Murillo was arrested at his residence in Mexico City and said he did not resist.
According to the initial investigations he led, the students had been killed and burned in a rubbish dump.
This thesis was later rejected by independent experts.
In addition, witnesses are said to have been tortured.
Perpetrators were corrupt police officers
Corrupt police officers kidnapped the students from the Ayotzinapa teacher training college in Iguala, Guerrero state, in September 2014 and handed them over to the Guerreros Unidos criminal syndicate.
Also against soldiers and employees of other authorities is determined.
The background of the fact is still not fully elucidated.
The Attorney General's Office will continue to work to bring those responsible to account, said head of state Andrés Manuel López Obrador on Friday in the northern city of Tijuana at his daily press conference.
"We've said from the start that we're telling the truth, no matter how painful it may be," López Obrador said.
The young men's parents wanted to thoroughly analyze the truth commission's report before commenting.
The content was very hard for them, said the human rights organization Centro Prodh.
So far, the students had been sought on the assumption that they might still be alive.
The Commission was set up almost four years ago.
It consists of government officials, students' families and professionals.