During 2014-15 Sweden received asylum applications from more than 240.000
people, of which more than 40.000 were termed unaccompanied minors. In a large
number of cases, claims by asylum seekers of being below 18 years were not
trusted by Swedish authorities. To handle the situation, the Swedish national
board of forensic medicine (R\"attsmedicinalverket, RMV) was assigned by the
government to create a centralized system for medical age assessments. RMV
introduced a procedure including two biological age indicators; x-ray of the
third molars and magnetic resonance imaging of the distal femoral epiphysis. In
2017 a total of 9617 males and 337 females were subjected to this procedure. No
validation study for the procedure was however published, and the observed
number of cases with different maturity combinations in teeth and femur were
unexpected given the claims originally made by RMV. Such unexpected results
might be caused by systematic errors and need to be analysed thoroughly. In the
present paper we present a general stochastic model enabling us to study which
combinations of age indicator model parameters and age population profiles are
consistent with the observed 2017 data for males. We find that, contrary to
some RMV claims, maturity of the femur, as observed by RMV, appears on average
well before maturity of teeth. Although results naturally contain much
uncertainty, we find that classification error rates for certain groups who
based on the RMV procedure are classified as above 18 years may be around
10-30%, possibly as high as 50%
