Mayor Nicolas Feraud is named as a defendant in one of the prosecutors' documents seen by Reuters summoning him for questioning on April 13.
He did not immediately respond to a request for comment.
Feraud, in his 50s, has previously admitted that the municipality missed multiple annual safety checks.
"We are deeply sorry. We had no indication that the checks had not been done as requested," Feraud told reporters in January.
The prosecutor's office in the Valais canton confirmed to Reuters that new individuals had been placed under investigation in the case, which involves suspected crimes including negligent homicide, without giving details.
The documents named four other past and present local officials in the Valais canton whom Reuters is not identifying under Swiss privacy laws.
The fire that tore through the Le Constellation bar on January 1 was one of the worst disasters in modern Swiss history and has strained relations with neighbouring Italy, which lost six citizens in the blaze.
Many young people remain in hospital with burn injuries.
The tragedy has also rattled the lucrative tourism sector.
The affluent town of Crans-Montana is popular among French, Italian and US tourists and known both for its sunny, south-facing ski slopes and its golf courses.
Prosecutors' inquiries initially focused on the French bar owners, who remain under investigation.
The probe was expanded in late January to include a current and a former local official.
Bar owners Jacques and Jessica Moretti have both voiced grief over the fire and said they would co-operate with the investigation.
The case now has nine defendants who, if convicted, could face a maximum penalty of four and a half years in prison.
