The complaint does not relate to the superintendent's role within the force, Wiltshire Police said.
An investigation is being carried out by another force after the incident was referred to the police watchdog.
A spokesman for Wiltshire Police said the officer had not been arrested, but had been interviewed under caution by detectives.
He added: "An investigation by an external police force has begun and in order to preserve the integrity of the investigation. It would be inappropriate for us to comment further at this stage.
"It's important to note that suspension is not an indication of guilt, but is sometimes a necessary part of the process."
The matter had been voluntarily referred to the Independent Police Complaints Commission (IPCC) which decided the matter could be investigated by an external police force.
A Wiltshire Police officer has been suspended following an allegation of fraud.