BOSTON — A federal appeals court has reversed some of the convictions against Maine’s former top drug prosecutor, who was sentenced to 16 years for child pornography.

The 1st U.S. Circuit Court of Appeals on Wednesday upheld convictions against James Cameron on seven counts but vacated convictions on six counts.

Cameron, 50, formerly of Hallowell and most recently of Rome, was convicted in August 2010 of 13 charges of transportation, receipt and possession of child pornography stemming from 2006 and 2007. He was sentenced in March 2011 to 16 years in federal prison but was freed five months later while his convictions were appealed. He has been free on unsecured bail since then.

The case now goes back to U.S. District Court in Maine for resentencing. Assistant U.S. Attorney Don Clark said no decision has been made about whether to pursue a new trial.

Part of Cameron’s appeal focused on the admissibility of evidence. The appeals panel found that Cameron in effect was denied his right to confront his accuser because some records used as evidence required calling a witness to authenticate them.

Cameron previously served as the chief drug crimes prosecutor in the Maine Office of the Attorney General, where he spent 18 years as an assistant attorney general.

He became the target of an investigation after the National Center for Missing and Exploited Children reported Yahoo had found multiple images of child pornography in a Yahoo! account belonging to Cameron’s wife.

He was fired from the Office of the Maine Attorney General in April 2008 and indicted on the child pornography charges Feb. 11, 2009.

Cameron was convicted of 13 charges on Aug. 23, 2010, after a six-day nonjury trial in federal court in Portland. U.S. District Court Judge John A. Woodcock, who presided over the trial, also imposed the sentence.

Under Cameron’s conditions of release, he was ordered to submit to active GPS monitoring; register with “all pertinent sex offender registries”; report in person to a probation officer; post an unsecured $75,000 bond; adhere to a curfew as set by a supervising officer; and participate in Internet monitoring, for which Cameron must pay.

In an opinion written by Circuit Judge Juan Torruella, the three-judge appeals court panel ruled that the indictment was sufficient, the trial venue in Maine was proper and Yahoo’s searches of Cameron’s accounts for child pornography did not violate the Fourth Amendment, so a suppression motion was properly denied.

The appeals court also said it concluded “that the district court did not err in admitting evidence from Yahoo! or the Google Hello Connection Logs.

However, the justices said Cameron should have had the opportunity to cross-examine Yahoo employees who prepared the child pornography reports. They said that allowing the reports to be admitted “violated Cameron’s rights under the Confrontation Clause,” and in turn tainted the CyberTipline Reports.

Circuit Judge Jeffrey Howard, in a dissent, said he supported the district court’s admission of those records.

Boston attorney Peter C. Horstmann, who represented Cameron in the appeal, could not be reached by phone at his office Wednesday night.

Anthony Vitarelli, of the Criminal Division Appellate Section U.S. Department of Justice, also could not be reached by phone at his office in Washington, D.C.