Shaun Edward Davidson, the Australian who recently escaped from Bali's notorious Kerobokan prison, may have drowned in the tunnel police allege he used to escape.
A head torch, which was still turned on, was discovered in the 15 metre tunnel which connected the prison to the outside world.
Since the four prisoners were discovered missing early Monday morning, there has been no sign of the men.
Police will use scuba and breathing gear to search the tunnel after heavy rain flooded it yesterday.
Badung District Police Chief Yudith Satriya Hananta insisted on searching the tunnel to ensure the men are not stuck in the mud.
"The tunnel is quite long, it's very possible that they got stuck with that small diameter of just 40cm. Let's drain it first [of water] and we'll see. If it's still filled, we can't [see it]. We need to make sure," he told reporters.
Next to the tunnel, authorities found two buckets, a towel, cups and sandals, as well as a fork inside.
The Corrections chief of the Bali Law and Human Rights Ministry, Surung Pasaribu confirmed they are checking the tunnel, but are also investigating whether the men had escaped through any jail gates or used a garbage truck.
"There is no sign of them. Only God knows. Hopefully they are fine," Mr Pasaribu said.
If the four did escape, many are postulating they have already seeped across the Indonesian borders on a boat.
All Indonesian airports and departure gates are scouting for the four escapees.
Although authorities assume the men don't have their passports, there's confusion over the whereabouts of the documents.
Mr Pasaribu confirmed the ministry didn't have the passport, nor did immigration, and prosecutors also claim they don't have them.
With only two months and 15 days left of Mr Davidson's sentence, the escape has shocked many.
Some are suggesting he escaped to avoid returning to Australia, where a warrant still stands for his arrest after being charged with possession of drugs with intent to sell or supply.