They are more likely to be ugly:
Being very attractive reduces a young adult’s propensity for criminal activity and being unattractive increases it. Being very attractive is also positively associated with wages and with adult vocabulary test scores, which implies that beauty may have an impact on human capital formation. The results suggest that a labor market penalty provides a direct incentive for unattractive individuals toward criminal activity. The level of beauty in high school is associated with criminal propensity seven to eight years later, which seems to be due to the impact of beauty in high school on human capital formation, although this avenue seems to be effective for females only.
Source: “Ugly Criminals” from “The Review of Economics and Statistics”
In the 19th century criminals were heavier, but that changed in the 20th century:
This paper considers the extent to which crime in the 19th century was conditioned on body weight. With data on inmates incarcerated in the Tennessee and Illinois state penitentiaries between 1831 and 1892, we estimate the parameters of Wiebull proportional hazard specifications of the individual crime hazard. Our results reveal that consistent with a theory in which body weight can be a source of labor market disadvantage, crime in the 19th century does appear to have been conditioned on body weight. However, in contrast to the 20th century, in which labor market disadvantage increases with respect to body weight, in the 19th century labor market disadvantage decreased with respect to body weight, causing individual crime hazards to decrease with respect to body weight. We find that such a relationship is consistent with a 19th century complementarity between body weight and typical jobs that required adequate nutrition and caloric intake to support normal work effort and performance.
Source: “Crime and Body Weight in the Nineteenth Century: Was there a Relationship between Brawn, Employment Opportunities and Crime?” from “National Bureau of Economic Research”, NBER Working Paper No. 15099