The 31-year-old was arrested on Friday and is now being remanded in custody for probable cause, which is the stronger degree of suspicion.
The man is known to the police.
As recently as last Friday, the man was sentenced to a daily fine for two cases of minor drug offenses and for carrying a knife on Annavägen in Växjö.
The incident for which he was convicted took place two days before the big fire.
Three people suspected
Previously, two people have been detained on suspicion of involvement in the fire: a woman in her 25s who is suspected of aiding and abetting a serious arson, and a man in his 50s who is suspected of a serious arson.
However, both were released at the end of last week, as prosecutors did not find sufficient grounds for arrest.
The man in his 50s was arrested as a reasonable suspect, the lower degree of suspicion.
- The criminal suspicions against the two remain, says Robert Loeffel, the police's press spokesperson in the southern region.
The police are silent about what the three people have in common with each other.
- They are in one way or another connected to the fire site, says Robert Loeffel.
Arrest proceedings will take place on Tuesday morning.