A St. Paul man was charged Thursday with sexually assaulting two young females who were playmates of his son, according to court documents.

Mark A. Busse, 42, faces two counts of first-degree criminal sexual conduct stemming from the assaults that allegedly occurred between 2007 and 2008.

According to the charges, authorities were alerted in September 2009 to child porn on Busse's laptop. Busse lived in an apartment complex were the two alleged victims had lived with their families in 2007 and 2008.

A search of Busse's apartment in 2009 found images and video files of the two girls, both now 8, on his computer, charges said. The images showed Busse sexually assaulting both girls, according to the complaint.

The girls' parents told investigators that the girls would visit Busse's apartment to play with his son.

CHAO XIONG