SAN FRANCISCO (CBS SF) — After a lengthy investigation, San Francisco police detectives have arrested a University of California,┬áSan Francisco psychiatry resident and his housemate on charges of unloading and trading child pornography on the internet, authorities announced Thursday.

Authorities said 36-year-old Billy Lockhart has been charged with possession of child pornography, possession of over 600 files of child pornography, and distribution of child pornography.

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Lockhard is listed on the UCSF website as a psychiatry resident in the Class of 2019.

Detectives with the SFPD Internet Crimes Against Children unit began investigating Lockhart in March. During that time they determined that he had used the UCSF internet network to upload child pornography.

Armed with a warrant, detectives searched Lockhart’s residence in the 100 block of Buena Vista Terrace.

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During the search, investigators located numerous media devices belonging to Lockhart, which all contained hundreds of child pornography videos and images.

Investigators were able to gather evidence that Lockhart was also viewing child pornography. Another resident at the home was also arrested, 33-year-old Benjamin Martin. Investigators located hundreds of child files on media devices belonging to Martin.

Both were arrested at the home.

Martin was charged for possession of child pornography, and possession of over 600 files of child pornography.

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Police urged anyone who may have been a victim or had any suspicious contact with Lockhart or Martin to contact the SFPD Special Victims Unit at (415) 558-5500.