Police in Manassas City, Virginia and Prince William County prosecutors are taking a unique approach to collecting evidence in a “sexting” case involving a 17-year-old male: Authorities want to take a photo of the teen’s erect genitalia to compare with a cellphone video, his attorneys said.

The case in Northern Virginia has sparked anger from the boy’s family, local lawyers and legal observers, who say that the amount of time and resources spent by law enforcement on private messages between teens is excessive.

The teen’s attorneys are particularly incensed that investigators want to take him to a hospital for an injection that would force him to become erect.

The teen is facing two felony charges in juvenile court, manufacturing and distributing child pornography, which could lead not only to incarceration until he’s 21 but also to inclusion on the state sex offender registry, at a judge’s discretion, for the rest of his life.

“The prosecutor’s job is to seek justice,” said the teen’s defense attorney, Jessica Harbeson Foster. “What is just about this? How does this advance the interest of the Commonwealth? . . . Taking him down to the hospital so he can get an erection in front of all those cops, that’s traumatizing.”

Manassas City police released a statement Wednesday night saying that the case was opened because the teen allegedly sent “pornographic videos . . . after repeatedly being told to stop.” The police said it was not their policy, nor the prosecutors’, “to authorize invasive search procedures of suspects in cases of this nature, and no such procedures have been conducted in this case.

Foster said the case began in January when the teen’s 15-year-old girlfriend sent photos of herself to the 17-year-old, who in turn sent her the video in question.