Freiburg prosecutor Dieter Inhofer confirmed on Saturday that a 17-year-old Afghan had been detained a day earlier. The suspect arrived in Germany in 2015 as an unaccompanied asylum seeker. He had since lived with a family.

The 19-year-old victim was sexually abused and murdered on the way home from a student party. Her body was found in the Dreisam river on October 16th.

According to police, a special commission of 40 investigators found an 18.5-centimeter-long black and bleached blonde hair in a thorn bush, as well as a vital black scarf in the riverbed of the Dreisam - just meters from where the victim's bike was found. During the search, investigators examined three bags full of thorn bushes alone.

DNA was found not only on the corpse, but also on the brake and shift levers of an abandoned bike close to the scene, police said.

The cause of death was drowning, the head of the special commission, David Mueller, reported.

Jogger case still unexplained

Investigators also studied video footage from Freiburg's local transport network which showed a suspect with a striking, black undercut hairstyle. The alleged perpetrator has so far remained silent. Whether there was any kind of relationship between him and the victim remains at the center of the investigation.

The case of a 27-year-old jogger who was raped and murdered at the beginning of November in Endingen near Freiburg also remains unsolved.

"We have no connection to the killing in Endingen," Inhofer said at Saturday's press conference.

ksb/cmk (AFP, dpa)