"I have never heard of anything like this, it is startling," said district prosecutor Anna-Karin von Schoultz.
The 31-year-old was not allowed any contact with the outside so he couldn't jeopardise the preliminary investigation into a gruesome stabbing that occurred in Växjö last autumn.
Yet during his time in custody the man sent an average of 90 text messages per day. The personnel at the remand facility noticed nothing.
"We received information as early as during the preliminary investigation that the man was able to communicate with the outside world," von Schoultz told local paper Smålandstidningen.
The police then started mapping the phone traffic and their investigation shows that the man started using the mobile about a month after he was taken into custody.
The calls and texts only subsided when one of the witnesses testified that he had been in contact with the man.
According to Smålandstidningen the man was in regular contact with several key witnesses in the murder investigation and sometimes spoke on the phone for up to an hour.
In order to get to the bottom with the matter the man was transferred to another jail. His cell was searched repeatedly but no phone was found.
However, police were able to see from the mobile phone traffic that he managed to bring the phone with him both to the new holding facility in Jönköping and back again.
The allegations are grave against the two prisons in Växjö and Jönköping.
Joakim Ringek, regional head of the Swedish Prison and Probation Service (Kriminalvården), did not want to comment on the ongoing misconduct investigation.
“But hypothetically speaking it is very serious if a detained individual have been able to communicate with the outside world,” said Ringek.
Since the investigations were initiated the man has undergone body searches and police have repeatedly searched the cells he have been detained in. No phone has so far been found.
The man was convicted to 12 years in prison by Växjö District Court in February but has appealed the verdict.
The case will come up in the Court of Appeal next week. The man remains adamant he is innocent.