Gardai have identified an apartment where they believe a serious sexual assault on a vulnerable young woman with learning difficulties took place.
Technical bureau officers have now carried out a detailed forensic examination of the scene and officers say the results will be crucial to their inquiries.
They hope the outcome of the examination will prove that the attack was carried out there as the victim has not yet positively pinpointed where she was assaulted.
Investigators have not yet identified the attacker.
But gardai believe the attacker knew some of the local residents and singled out his victim after approaching at least two other women earlier on Wednesday afternoon.
The victim, who is in her mid-20s, was sexually assaulted in a flat, which is in the general area of the South Circular Road/ South Richmond Street/Portobello in Dublin.
Detectives are building up a picture of the attacker. He was described last night by one witness as being dark-skinned, with black hair and of medium height.
Officers have also spoken to two women, who contacted the investigation headquarters at Kevin Street station to report that they had been approached on the street by a man they believed to be the attacker.
The victim had been jogging with her mother along the South Circular Road when they became separated.
Gardai said it was not unusual for the woman to part from her mother while jogging.
The woman returned home on Wednesday after being missing for about an hour and told her parents about the assault.
Gardai were alerted and the woman was taken to the sexual assault unit at the Rotunda hospital for treatment.
The victim was approached by her attacker as she jogged towards Harrington Street between 4pm and 4.15pm and they walked in the direction of the Victoria Street/Lennox Street area.
She is described as 4ft 10ins tall, with shoulder-length brown hair. She was wearing a black cardigan, beige top, black knee length leggings and white runners.
Gardai have appealed to anyone, who saw the victim in the company of the dark-skinned man in any of those areas, or who has any other information about the incident, to contact them at Kevin Street station on 01 666 9400 or on the confidential line, 1800 666111.
Officers also asked anybody who had private CCTV cameras in their vehicles or on property to get in touch.