"The person is the first to be detained for both murders, both kidnappings," prosecutor Hanna Cardell told the newspaper, adding that the man is believed to be abroad.
One of the boys, Mohamed, was found dead in Nynäshamn, south of Stockholm, at the end of July. Mohamed has been placed in a residential care home in Nyköping for some time. But the weekend before the murder, he was visiting his family in Nässjö.
The remains of the second boy, Layth, were found in Upplands-Bro, north of the capital, at the end of August. Both boys had disappeared from residential care homes in Nyköping.
Confirmed: The murders are suspected to be connected
Hanna Cardell confirms to Svenska Dagbladet that the cases are suspected to be connected.
"There is a suspected connection to network crime," she told the newspaper.
Three people – aged 15, 17 and 25 – are already suspected of involvement in the murder in Upplands-Bro, while three other people are detained in the Nynäshamn case.