"Lab tests of samples...revealed the genetic profile of a single person, respectively Alexandra Macesanu, scientifically based on the comparison of this genetic profile with Alexandra's parents' DNA," the DIICOT directorate for investigating organized crime and terrorism, said in a statement.
Macesanu's uncle Alexandru Cumpanasu, who has been acting as spokesman for the family, said late on Friday on his Facebook page the justice minister "had notified my cousin," on the DNA results.
A 65-year-old mechanic from the southern Romanian town of Caracal has confessed to killing Alexandra Macesanu, who went missing on July 24, and another 18-year-old girl last seen in April.
Macesanu phoned the European emergency number 112 three times to say she had been kidnapped, beaten and raped. It took authorities 19 hours to locate and enter the mechanic's residence as they struggled to trace her calls and secure unnecessary search warrants.
On site, authorities found bone fragments and collected DNA samples, but a preliminary forensics report has yet to be released.
"I have not lost trust, I believe she is still alive, I cannot wait to see her," Ioan Macesanu, the father of the girl, told reporters late on Thursday.
The authorities' handling of the case has triggered street protests in cities across the country. The interior minister has resigned, while the chief of Romanian police and several other officials were fired.Prosecutors are investigating those responsible for the slow response. President Klaus Iohannis said that a preliminary inquiry has shown politicized public safety bodies to be under-funded, short-staffed and insufficiently trained.