Police have found the remains of at least 240 people thought to have been killed by a single hitman who used acid to dissolve his victims in barrels before dumping them in mass graves, wrote dailymail.co.uk

The method gave the suspected murderer the nickname of The Soup Maker, and investigators believe there could be as many as 650 victims buried in the spot in Tijuana used by the killer. 

Authorities believe the area was used by Santiago Meza Lopez, known as El Pozolero, who is alleged to have worked for the Sinaloa Drug Cartel in Mexico. 

Hitman Lopez was arrested in 2009 and has been attributed with the murder of at least 300 people by a prosecutor, but is still awaiting sentencing.

Lopez is alleged to have put their bodies in barrels of acid before pouring the remains and the acid into the pits to dissolve the flesh and bone underground. 

Workers have so far found 16,500 litres of organic material and between 170 and 200 kilograms of human bones at the alleged killing grounds.

Authorities have estimated there could be up to 650 people buried at the site.

The human remains were found in an area known as The Chicken Coop in Tijuana, in the Mexican state of Baja California. 

The President of the United for the Disappeared of Baja California association, Fernando Ocegueda Flores, told reporters: 'These are those bodies we bagged on the last occasion. There are almost complete bodies.

'Of the 16,500 litres of organic material, the Federal Attorney General's Office said that there could be up to 650 bodies.' 

Digging at the site has been ongoing since the start of the decade after Lopez was put into custody pending his trial. 

In 2011, prosecutors unearthed fat, skin and bones at properties in the Mexican border city of Tijuana once used by The Soup Maker, who confessed to dissolving the bodies of drug cartel victims.

Anti-crime activist Fernando Ocegueda said seven years ago there was reason to believe the remains belong to victims of cartel body-handler Santiago Meza Lopez. 

In January 2009 Mexican police arrested Meza Lopez on suspicion of helping a drug kingpin dispose of hundreds of victims. 

The victims are believed to be rivals of Teodoro Garcia Simental, an alleged former lieutenant of the Tijuana-based Arellano Felix drug cartel, authorities said.

After his arrest Meza Lopez told how he allegedly disposed of the bodies and that he was paid £440 a week for his work.

Meza Lopez told police his busiest period was in December 2007 when he claimed to have disposed of 32 bodies.

The Sinaloa Cartelis an international drug trafficking, money laundering, and organized crime syndicate.

Established during the mid-1980s, the Sinaloa Cartel is based primarily in the city of Culiacan, Sinaloa, with operations in the Mexican states of Baja California, Durango, Sonora, and Chihuahua.