ARTICLE AD BOX
By Will Grant in Mexico & Adam Durbin in London
BBC News
Mexican prosecutors say they have identified eight suspects thought responsible for 38 deaths in a fire at a migrant detention centre.
Monday's blaze is now being investigated as a possible homicide.
Five of the suspects are reported to be security guards at the facility in Ciudad Juarez, a city on the US border.
Authorities are facing mounting pressure to explain why the victims, who came from Central and Southern America, were not freed.
Mexican President Andrés Manuel López Obrador said those responsible would be punished "in conformity with the law".
Speaking at a press briefing, he insisted there would be transparency in the investigation and "no impunity" for those responsible for the "painful tragedy".
Shortly after the fire, Mr López Obrador said the migrants had set mattresses alight "when they learned that they'd be deported".
However, there are reports that migrants were detained at random during a roundup, were being held in poor conditions and were not being given enough water while in detention.
The most pressing question being asked in Mexico, particularly by other migrants in Ciudad Juarez and human rights groups, is why did the guards fail to free the detainees once the blaze had begun?
A 30-second video, reportedly from security cameras inside the facility, appears to show at least one man attempting to open the door while several guards move around outside before leaving as the flames engulf the room.
The footage has been widely shared on Twitter and published by a number of Mexican newspapers, with many people expressing shock at what they say was a failure by the guards to act.
Asked about that footage, Mr López Obrador - who has a very fractious relationship with the media - accused journalists of being more interested in sensationalism than the pain of the trapped migrants.
Mexican officials say a total of 68 men were in the facility at the time of the blaze. The majority were from Guatemala, with the others from Colombia, Ecuador, El Salvador, Honduras and Venezuela.
Authorities have released their names, but have not yet clarified which of them are dead and which have survived. Twenty-eight of them are reported to be seriously injured.
The fire comes at a time when Mexico is struggling to deal with an influx of migrants, most of whom are crossing the country in the hope of reaching the US.