Temporary Assistant Chief Constable Pat Campbell was referred to the Police Investigations and Review Commissioner (PIRC) after a complaint was made against him in December.
The watchdog later submitted their findings about the incident, which allegedly took place at a cyber conference, to the Crown Office and Procurator Fiscal Service (COPFS) on February 18.
Mr Campbell is the most senior officer to be investigated by the PIRC to date.
A spokesperson for the COPFS said that woman who made the allegations had the right to review its decision, adding: “Those directly involved have been informed of an update in this case and that there is a right to call for a review.
“Until any review has been completed the question of whether or not there will be a prosecution remains open.
“The Crown reserves the right to proceed and will not comment further at this time.”
When a review is undertaken, it is conducted by a prosecutor who has not had previous involvement in the case.
A senior officer can be suspended if an allegation, if proven, would be sufficiently serious to amount to misconduct or if the nature of the allegation means suspension is in the public interest.
In February, The Scotsman revealed that a more than 100 serving police officers have been subject to sexual offence allegations since 2014, with 20 convicted.
Just five officers were dismissed following internal investigations, with 17 allowed to resign or retire following investigation of the alleged misconduct, figures show.