MEXICO CITY, Jan. 27 -- Various evidence has proved that the 43 college students, missing in Mexico's southern state of Guerrero last year, were murdered and incinerated, said Mexico's top prosecutor on Tuesday.

Attorney General Jesus Murillo Karam told a press conference that testimony from some perpetrators and results of police investigations have led to the conclusion.

"That is the historical truth of the events," Murillo said, reaffirming the government's preliminary assertion following a clash between the students and local police in September 2014 in the city of Iguala in Mexico's violence-torn southern state of Guerrero. The policemen are believed to have links with drug gang members.

The conclusion is based on testimony from 39 police officers, 487 investigations and 386 statements, all of which have led to the arrests of 99 suspects, said Murillo.

Felipe Rodriguez Salgado, known as "El Cepillo" or "The Brush," recently captured in central Mexico, also confirmed the testimony and accounts of those arrested previously, said the prosecutor.

Rodriguez, a member of a Guerrero-based criminal ring called Guerreros Unidos, told the authorities that he and another dozen men were ordered to go to an area known as Loma de Coyote, where local police from Iguala and nearby Cocula handed over the students.

The arrested said they took the students to a garbage dump in Cocula, where they were executed and incinerated. Their ashes were then thrown into the San Juan Cocula River.

Parents of the missing have been demanding the government continue to search for the students whose remains have not been identified and investigate the army's role in the incident.

The attorney general said, however, "there isn't a single piece of evidence" that the army had a role in the killing.

The fact that the remains of one student, Alexander Mora Venancio, were identified has also proved the authorities' judgement, while experts in Austria are still working to identify the remaining victims, Murillo added.

According to the Mexican daily La Jornada, Murillo said the case has to be closed before the authorities can convict and sentence the suspects in custody, even though other suspects have yet to be seized.

The mayor of Iguala, who allegedly had ordered the killings, and his wife are among the 99 people arrested so far in connection with the crime.