Gardaí will send a file to the Director of Public Prosecutions in relation to the case, which was described by one source as being a matter of “grave concern”.
A teacher at the facility, in north Dublin, was questioned in connection with allegations that a girl with special needs attending the school had been abused.
There was also a suggestion that photographs may have been taken.
Gardaí were yesterday liaising with management at the facility.
It is understood gardaí began investigating after the girl indicated she was afraid to attend the facility. Her parents then contacted gardaí, who followed up the allegation of sexual assault.
It is understood the person questioned is a qualified montessori teacher and had been at the school for some time, having previously worked at other facilities.
It is believed the man was arrested on Thursday and questioned but was released without charge yesterday.
Parents of other children attending the facility were notified, although it is understood no other allegations have been made.
The parents of the girl who was allegedly abused have been described as “very upset” and “traumatised” by developments.
It is understood the man would have had to have undergone Garda vetting to work at the school.
A HSE spokesperson said yesterday it did not have a role in taking over operations at the facility.