ACAPULCO, Mexico -- A grisly YouTube video allegedly posted by a Mexican drug gang led investigators Wednesday to a mass grave containing 19 bodies believed to Mexican tourists kidnapped while visiting the iconic resort city of Acapulco.

Fernando Monreal, investigative police chief for Guerrero state, told the Associated Press that investigators have not confirmed if the bodies found in the grace in Tres Palos, a town just south of Acapulco, were those of 20 men who were kidnapped on Sept. 30 while visiting the tourist destination from neighboring Michoacan state.

Investigators began focusing on the site after a video appeared on YouTube featuring two men who answered questions from an unseen interrogator as their hands were apparently bound. In the video, the unidentified men say they killed "the Michoacanos" and buried them nearby.

Two bodies wearing identical clothing as the pair seen in the video were later found on top of the grave, along with a sign that read: "The people they killed are buried here."

The two men say they killed the "Michaocanos" in an act of revenge against La Familia, a drug cartel based in Michoacan. Police have yet to confirm the identities of the bodies found on top of the grave.

The families of the 20 missing men have publicly said they were mechanics in the state capital of Morelia who saved up money to take a vacation together.

Guerrero state investigators say they corroborated the men worked as mechanics and had no criminal records. Investigators also say they could find no evidence linking the men to any gang and have speculated the group may have been targeted by mistake.

The kidnapping was one of the biggest blows yet to Acapulco, which has seen an increase in drug-gang shootouts, beheadings and kidnappings. Even Acapulco Mayor Jose Luis Avila Sanchez recently urged residents to stay indoors after nightfall, an extraordinary pronouncement in a city that depends on nightclubs, bars and restaurants.

If the video's claim is confirmed, it would be a chilling example of a growing trend that has added a new dimension of terror to Mexico's bloody drug war: cartels releasing footage of kidnapped people admitting at gunpoint to crimes from extortion to murder. It is often impossible to determine the veracity of confessions given under duress.

In the boldest case, a video emerged less than two weeks ago showing the kidnapped brother of Patricia Gonzalez, the former attorney general of northern Chihuahua state. In the video, the brother, Mario Gonzalez, says his sister protected a street gang tied to the Juarez cartel and was behind several murders.

Gonzalez, who had been kidnapped days earlier, made the statement while sitting handcuffed in a chair surrounded by five masked men pointing guns at him. His whereabouts remain unknown.

Patricia Gonzalez denied any links to drug traffickers and said she is sure her brother spoke out of fear.

The Associated Press contributed to this report.