The investigation into the firing in Sonbhadra district in Uttar Pradesh, which left 10 people dead last week, might face a hurdle as the 1955 revenue records of the disputed land are missing, PTI reported on Tuesday.

“The records of the land belong to the time when Sonbhadra was a part of Mirzapur district, till 1989,” Additional District Magistrate Yogendra Bahadur Singh told PTI. “Some records are destroyed after a specified period of time. The same is the case here.” The police officer said that some records, which are considered time-barred, were destroyed in a routine manner.

On Saturday, Uttar Pradesh Chief Minister Adityanath had blamed the Congress for the violence in Sonbhadra, saying the basis of the land dispute was laid in 1955 during the Opposition party’s rule.

“This incident is a very big political conspiracy,” the chief minister had alleged. “The foundations were laid in 1955 when this land was transferred to a trust. In 1989, Congress government in UP transferred the land [back] to individual members.” Later, the individual reportedly sold the land to gram pradhan Yagya Dutt, who is the main accused in the firing last week.

Adityanath had named a committee to look into the firing, and said that the report should be submitted within 10 days. The chief minister also met the family members of those killed in the shootout.

The incident has snowballed into a political controversy. Congress General Secretary Priyanka Gandhi attempted to visit Sonbhadra on Friday, but was detained and taken to a guesthouse, where she stayed on Friday night. The next day, Gandhi was allowed to meet the families of two victims. A Trinamool Congress delegation also tried to visit the district, but was stopped, and then sat on a dharna at Varanasi airport.