A civilian employee at the Aberdeen Proving Ground on Wednesday pleaded guilty in federal court in Baltimore to two counts of possessing child pornography, Maryland U.S. Attorney Rod J. Rosenstein said.

David Earl Jones, 42, of Jarrettsville, Md., was found to have 186 videos and 650 photos of unsuspecting, undressed girls and women, authorities said. The photos and videos were taken through windows from outside the homes of the victims, federal prosecutors said.

Authorities said the investigation was launched in April 2010 after a 911 caller reported that a man was outside a Maryland home taking photos through a window of a teenage girl who was nude in her bedroom. Deputies responded and Jones was arrested, court papers say.

After his arrest, Jones was permitted to make a telephone call, according to the plea agreement. In that call he asked someone to delete his Facebook account and he “apologized for what he had done.”

Police seized computers, compact discs and DVDs from Jones’s home and workplace, officials said. They found 186 videos and 650 photos of naked women and girls in their homes. The victims did not know they were being filmed.

Authorities said they have been able to identify at least seven victims who are or were minors when the photos and videos were taken, and one adult. In some cases, the victims have not been identified because their faces are not visible.

Each of the minor victims attended the same school, and authorities found what appeared to be yearbook photos of these girls in his computer as well. Jones recorded and photographed his victims on different dates, sometimes over a period of years, authorities said.

Among the victims was a girl who was in Jones’s care, prosecutors said. Authorities said he videotaped the girl over about a five-year period, beginning when she was 13-years-old. In all, authorities said, Jones, who would hide in closets and outside windows, took at least 61 video images and 156 photos of the girl.

As part of his plea agreement, Jones must register as a sex offender.

If U.S. District Judge Catherine C. Blake accepts the plea deal, Jones will be sentenced to 12 years in prison, followed by a lifetime of supervised release.

Blake has yet to schedule a sentencing date.

The case was brought as part of Project Safe Childhood, a nationwide effort by the Justice Department to combat child sexual abuse.

Last month, a captain in a local police department in Connecticut was charged with child pornography as part of Project Safe Childhood.