Chinese police have issued a public notice offering a 1 million yuan ($140,000) reward to anyone able to assist with recovering a pair of priceless stone lions that were stolen from a Tang dynasty emperor’s mausoleum 14 years ago.

The notice, released on Monday, is the latest move in an epic investigation that has seen officers travel across China, follow up on hundreds of leads, and conduct tens of thousands of interviews in their ongoing struggle to solve one of the most mysterious heists in decades.

The 2-ton stone lions have unique artistic and historical value. For over 1,000 years, they guarded the eastern entrance to the mausoleum of Tang Suzong, the eighth emperor of the powerful Tang dynasty (618-907), who died in the 8th century.

The intricately carved statues, standing around 1.5 meters tall, depict a pair of squatting lions, their four legs seamlessly connected to the base. One lion stares straight ahead with bared teeth, while the other growls and sticks out its tongue aggressively.

“The stone carvings are the most preserved, complete, and exquisite among the 18 Tang dynasty imperial mausoleums existing today,” Xie Gaowen, director of the Xianyang Institute of Archaeology, told domestic media in 2010.

But the relics vanished from the mausoleum in Liquan County, Shaanxi province, on the morning of April 3, 2010. Arriving at the scene, officers found only a pair of plinths, along with detritus left behind by the robbers.

Based on evidence discovered at the mausoleum, police concluded the heist was conducted by a group of individuals who used scaffolding, chains, and a motorized tricycle to move the heavy statues. But from the beginning, the investigation was hampered by an almost total lack of valuable leads.

The mausoleum’s remote location — the eastern gate is 2.5 kilometers from the nearest village — as well as a cold snap that kept most locals indoors meant that few witnesses came forward to report seeing any suspicious persons either before or after the theft.

Local police have invested considerable resources in tracking down the perpetrators. Officers have reportedly traveled to multiple provinces, screened over 1,000 potential suspects, interviewed over 50,000 people, and verified over 500 clues, solving a number of related cases in the process.

However, after over a decade of work, authorities have yet to unravel what happened to the stone lions, which China has listed as national-level cultural relics. “The police have been working hard on the case for the past decade,” a spokesperson from the Liquan County Public Security Bureau told domestic media in 2020. “The current difficulty in handling the case is the lack of clues.”

Over the years, police have offered ever greater rewards for tip offs about the case. In 2010, the amount was set at 100,000 yuan, then doubled seven months later. By 2020, the reward had reached 1 million yuan. However, the police’s move to issue a fresh notice this week indicates that the previous offers failed to lead to any breakthroughs.

When reached by Sixth Tone, a police officer surnamed Wang who is working on the case in Liquan County said that he could not disclose further information about the progress of the investigation.

In the meantime, Chinese authorities have been working to prevent similar heists from occurring. Soon after the stone lions disappeared, officials in Liquan County moved over 10 historical artifacts deemed at high risk of theft to storage. This included four stone lions guarding the western and northern gates of Tang Suzong’s mausoleum.

Authorities have made protecting cultural relics in sparsely populated and hard-to-reach locations a key priority over recent years. In 2020, Shaanxi province issued a directive requiring officials to set up regular patrols and install surveillance equipment at key sites. The technology mentioned included underground detection systems, surveillance drones, and solar-powered security cameras.

Additional reporting: Yin Ziyuan.

(Header image: Patrick Strattner/Getty Creative/VCG, re-edit by Sixth Tone)