Users of the Telegram social media app can set the time in which they want a message to be deleted automatically. Ryo Oyama A social media app developed in Russia in order to skirt censorship is proving to be the biggest roadblock for Japanese police investigating a recent string of scams and deadly robberies.
The four ringleaders that the Philippines deported earlier this month to Japan apparently used the Telegram app to send instructions to their underlings in Japan who carried out the actual crimes, including the suspected murder of a 90-year-old woman in Komae, western Tokyo.
The service has more than 700 million users around the world, according to its official website.
Telegram has a secret chat function that lets users set the time when a message is automatically deleted from the recipient's and the sender's devices. The records of the encrypted messages are not left in the service provider's computer system.
The fact that 15 or so mobile phones and tablet computers sent to Japanese police by their Philippine counterparts had almost no relevant data in them, police said.
It is not clear if the devices were rebooted or if messages were automatically deleted through the secret chat function. The instructions were sent by individuals using names such as Luffy and Kim. The Telegram app was developed by a Russian who was pressured by authorities to delete anti-government posts on another social media site operated by the developer, according to cybersecurity expert Koichiro Komiyama.
Telegram included several functions that were intended to protect the freedom of expression and privacy of the user, in order to avoid interference from the authorities.
Many of the instructional messages sent to those who carried out the crimes in Japan had been deleted, making it hard for Japanese police to determine the exact chain of command.
Daisuke Tanaka, 48, is president of Asueito Advisory Inc., a company that analyzes electronic equipment.
He said it is extremely difficult to analyze Telegram because the company hasn't made its encryption procedure open, nor has it revealed the location of the computer system used to operate the service.
Tanaka said that the operator won't cooperate with investigators because of anti-authority thinking at the root of the service.
At the same time, Tanaka said it is not impossible to reconstruct deleted messages.
He said it is possible to partially reconstruct messages, determine the sender and the time it was sent if the analytical tool is compatible with the device and its operating system.
Tanaka said there is a higher chance of obtaining messages that can be used as evidence if the sender forgot to use the secret chat function.
Investigative sources said that any analysis would take time because the 15 or so devices sent to Japan from the Philippines have a wide range of models and different app versions, which means different methods would have to be used for each device to reconstruct deleted messages.