Final answer:
Adolescents are the group that criminologists Miethe and Regoeczi suggest are increasingly characterizing youth homicides, which is supported by demographic trends and social environments.
Step-by-step explanation:
Criminologists Miethe and Regoeczi suggested that adolescents were increasingly characterizing youth homicides based on noticeable changes. This aligns with broader criminological findings that indicate a higher propensity for certain age groups, specifically younger individuals, to be involved in violent crimes, as suggested by demographic trends and social theories.
It is important to consider the broader context in which these trends occur, such as economic development levels and social environments. For instance, age structures of economically undeveloped countries show greater proportions of children, and these demographics can be correlated with different societal and criminological patterns.