MARTINEZ, Calif. -- A Martinez man previously accused of traveling across state lines for purposes of illegal sexual conduct with a 14-year-old Oregon girl is due to be arraigned in federal court in Oakland on Tuesday on expanded charges of producing and distributing child pornography.
Blake Robert Johnston, 41, was charged in a seven-count superseding indictment issued by a federal grand jury in Oakland last week. He will be arraigned Tuesday by U.S. Magistrate Donna Ryu.
Johnston, who has been held without bail since his arrest last October, was originally charged with one count of traveling for the purpose of engaging in illegal sexual conduct with a minor.
According to a federal criminal complaint filed in October, he was arrested by Martinez police late on the evening of Oct. 14 after officers found a missing 14-year-old girl from Salem, Oregon, in his bed at his home in Martinez.
Johnston was traced through cellphone records provided by the victim's mother.
The revised indictment includes the previous charge and new charges of transportation of a minor for sexual purposes, online enticement of a second minor victim, two counts of producing child pornography with a third and a fourth victim and two counts of distributing child pornography.
Prosecutors alleged in a status report filed Friday that agents have identified 31 other juvenile victims who had online contact with Johnston, most of whom allegedly sent him pornographic pictures of themselves at his request. The victims are from 12 U.S. states, the United Kingdom, Ireland and Australia, prosecutors said.
In addition, U.S. Customs and Immigration Enforcement investigators believe there could be as many as 300 other underage victims whose images allegedly appear in pornography found in Johnston's computer, prosecutors said.
Tatum King, the acting chief of ICE Homeland Security Investigations in San Francisco, said, "We're appealing to anyone who has awareness about this defendant's activities or his past contacts to come forward.
"Those leads could be vital to helping us put together the pieces of this puzzle and most important, to ensuring that any underage victims receive the assistance and support they may need," King said.
Anyone with information related to the case is urged to call the national toll-free tip line of Homeland Security Investigations at (866) DHS-2-ICE or the Martinez Police Department's tip line at 925-372-3457.