Over the weekend, a truck driver was detained and later released for allegedly ignoring warning signs and driving over a section of Peru’s ancient Nasca lines.

As Eli Rosenberg at The Washington Post writes, the semitrailer driver, identified as 40-year-old Jainer Jesus Flores Vigo, left tire marks in an area measuring roughly 164 by 328 feet that crossed over three of the Unesco World Heritage site’s enigmatic geoglyphs. Nicole Chavez at CNN reports that a judge later ruled there was no evidence that he acted with intent and that the damage was an unfortunate accident.

According to Laurel Wamsley at NPR, Flores Vigo told an Argentine newspaper that he pulled off the road and drove into the glyphs because he was experiencing trouble with his truck. However, the newspaper speculates that he may have left the Pan-American Highway, which cuts directly through the Nasca geoglyphs, in order to avoid paying tolls.

Authorities believe the tire tracks that the truck left across the glyphs can be repaired. Meanwhile, Peru's public minister has announced he plans to appeal the judge's decision and is seeking nine months of detention and a $1,550 fine for the driver while the investigation continues.

The area of geoglyphs covers 310 square miles, making it difficult to monitor everything that happens in the protected landscape. “While the Culture Ministry monitors areas with the largest concentration of geoglyphs every day, it [the site] may not be fully protected,” Johnny Isla, a spokesman of the Ica branch of Peru's Ministry of Culture, tells Peru news agency Andina. “Entry and transit are possible through valleys and streams where the archaeological area spreads out.”

Andina reports that the government of Peru is considering using drones to monitor the area, but it relies mainly on the local population which it has recruited and educated in recent years to monitor the ancient site.

According to National Geographic, the lines were found some 80 years ago and are only visible from the air. They include more than 800 straight lines, 300 geometric patterns and 70 plant and animal designs that range from 50 to 1,200 feet in length. The designs were created by removing about a foot of rock and sand from the desert, creating a lighter-colored negative image. Because the area of high desert where they are located receives so little rain, the geoglyphs have not weathered away. It’s believed that most of glyphs were created by the Nasca culture around 1 A.D. and 700 A.D. While some researchers believe the glyphs were part of a huge astronomical calendar, others believe they are related to rituals involving water.

Incidentally, this is not the first time the lines have been damaged in recent years. In 2014, at least 20 members of the environmental group Greenpeace walked onto the glyph field and laid fabric letters on the ground spelling out the message “The future is renewable” near a famous glyph of a stylized hummingbird. While the fabric did not do any damage, the activists were prosecuted for tromping across the site and leaving visible trails in the desert near the glyph.

In 2013, a company mining limestone in the desert was also prosecuted for destroying a set of lines and a trapezoid glyph when workers strayed into the protected area.