The resident of the Bernese Oberland was arrested on February 7th on suspicion of helping the extremist group by sending them a Czech pistol.
The pistol, traced to Switzerland, was linked to the death of nine immigrants between 2000 and 2006 and a police officer in 2007.
Justice authorities said there was no risk of the Bern man colluding with neo-Nazis in Germany.
However, Michael Fichter, spokesman for the Bern cantonal police, said the case continues to be investigated.
Another Swiss man was taken in for questioning in the affair in January.
Police say they have so far been unable to establish links between the two men and extreme-right German groups.
The Czech pistol is suspected to have been used by a neo-Nazi cell, consisting of two men and a woman, who lived in Zwickau, eastern Germany.
In addition to the suspected murders the group was implicated in bomb attacks in Cologne between 2001 and 2004 that injured 23 people.
The two men in the group committed suicide last autumn after a failed bank break-in.
The woman remains in detention.