More than two dozen bodies, some of which were dismembered, were found buried in a Mexican sugarcane field and authorities said Wednesday that they believe the deaths were drug-related.

Four graves containing the remains of 33 people were located in the township of Xalisco, part of the state of Nayarit. The area is known as a base for a black-tar heroin trafficking ring. The first pit contained the remains of nine bodies and trained dogs led searchers to three other pits nearby.

The gruesome findings follow an ongoing power struggle between drug gangs in the area after the March arrest of Edgar Veytia, the former state attorney general, who faces U.S. charges of drug smuggling.

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"The assumption is that these were people who were involved with one of the various criminal groups, but I can't say which one," current state Attorney General Petronilo Diaz said, referring to the bodies in the graves.

He added that disputes between gangs in the area is a result of Veytia’s arrest.

"That is when these criminal groups start fighting, and that's when this mess we're seeing started," Diaz said.

Corrupt officials in the country have sometimes favored one particular drug gang over another or divided territories as a way to maintain a sort of rough peace.

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The existence of the burial pits came to light when some families searching for missing loved ones found remains on Saturday after receiving a telephone tip from local residents.

Authorities said they’ll use DNA testing to identify most of the deceased individuals, which were already deep into the decomposition process by the time they were found. Only one body still had a legible tattoo that might help identify it, officials said.

Investigators think the bodies have been buried for about six months.

The Associated Press contributed to this report.