Dorset Police said a 19-year-old man and a 71-year-old woman were arrested in connection with the disappearance of Gaia Pope.
The teenager, from Langton Matravers, was staying at an address in Swanage when she disappeared on the afternoon of 7 November.
“I would appeal to anyone who has information about her disappearance to please contact Dorset Police.
Her disappearance sparked a massive campaign to find her, while detectives arrested three individuals who were later released without charge.
The body of Miss Pope was found on land south of Swanage last Saturday close to where some of her clothing had been recovered.
During the vigil a minute silence was observed by mourners.
“Our thoughts remain with them at this very difficult time.” Ms Pope was staying at an address in Swanage, Dorset, when she disappeared on 7 November.
Less than an hour before her last confirmed sighting at 3.39pm, she was being driven between Langton Matravers and Swanage by a family member when they stopped off for fuel at St Michael’s Garage on Valley Road in Swanage.
Mourners have joined for a vigil held in memory of teenager Gaia Pope who was found dead a week ago.