Eight men are already in custody connected to the case, which has sparked right-wing demonstrations, as well as counter-protests in the picturesque city located in the southwest state of Badem-Württemberg.
On Friday authorities said they had discovered two further sets of DNA traces that do not match any of the others suspects' DNA, raising suspicions that more suspects are involved.
“We have to assume that we are looking at two additional suspects,” Bernd Belle from Freiburg's criminal police force said at a news conference. He said investigations were continuing.
Several men are suspected of raping the victim after she had visited a nightclub in Freiburg on October 14th.
Police said the woman had taken drugs, but that it was unclear whether a drink she took afterwards was spiked.
It is understood the woman had left the club and the main suspect, a 22-year-old man, had gone with her. The victim was then allegedly raped. The man then reportedly went back to the club where he told other men that the woman was defenceless outside, and other men reportedly raped her.
The 22-year-old suspect was described by police as a multiple offender and is suspected of being involved in another case of sexual assault.
The eight suspects in custody are seven Syrian men aged 19 to 29-years-old and a 25-year-old German.
The victim is being supported and was described by police as being in a stable condition.
SEE MORE: Why Freiburg has been rocked by protests after shocking crime
'Asylum seekers should get sex education in Germany'
The update came as federal government integration commissioner, Annette Wildmann-Mauz (CDU) called for all asylum seekers who arrive in Germany to be given sex education.
WIldmann-Mauz demanded action following the rape case in Freiburg, calling for asylum seekers to attend courses on sex and equality.
“Immediately after their arrival in Germany, all asylum seekers must receive courses on life in Germany at the first reception facility – and this includes zero tolerance for sexual abuse and other acts of violence,” the CDU politician told the “RedaktionsNetzwerk Deutschland on Thursday.
The politician also called for asylum seekers, refugees and migrants already in Germany to mentor newcomers and supported violence prevention projects that train mentors to do this.
“Men who have been living here for some time must talk clearly to new immigrants about how sexuality and equality are practiced in Germany – if necessary also in their mother tongue,” Wildmann-Mauz said.
'Brought to justice'
The commissioner also urged swift punishment of the alleged perpetrators in Freiburg.
“The perpetrators must be brought to justice and severely punished,” she said,. “We are dealing with a heinous crime. Anyone who comes to our country and commits such crimes must be expelled”.
The human rights organization Pro Asyl (Pro Asylum) raised some concerns about the demand.
Managing director Günter Burkhardt told the newspaper Neue Osnabrücker Zeitung
on Friday that “one learns values and norms better in everyday life than in class”.
“Language courses, as many contacts as possible with volunteers, support at school and opportunities in the labour market – that is the best integration and the best prevention,” he said.
Burkhardt also warned against isolating asylum seekers in so-called anchor centres or other large shelters.
“Isolation promotes a climate of violence,” he said, but stressed that it was no excuse for crimes such as rape or murder.
“There are also criminals among refugees. They belong behind bars. Thousands of refugees in Germany are horrified by such acts of violence and fear that they will come under general suspicion.”
As we reported earlier this week, the case has shocked Germany and sparked protest in Freiburg. On Monday evening the Alternative for Germany (AfD) party organized a demonstration which was attended by about 500 people, calling for the country to be more secure and to allow less migrants or refugees into Germany.
But a counter-protest of around 1500 people were also out on the streets. They believed right-wing organizations were using the crime as an excuse to promote their anti-immigrant agenda.