A repeat sex offender will serve up to 30 years in state prison and must wear a Global Positioning System monitoring device for 10 years after his release for attacking and trying to rape a woman in a Massachusetts General Hospital bathroom late last year, Suffolk County District Attorney Daniel F. Conley said today.

Suffolk prosecutors had recommended that DAVID FLAVELL (D.O.B. 6/22/69) serve a term of 30 to 40 years behind bars. Superior Court Judge Charles Spurlock imposed a 25- to 30-year term but also ordered that Flavell serve 10 years of probation upon his release. During those 10 years, Flavell must wear a GPS device, stay away from the victim and the hospital, register as a sex offender, undergo sex offender evaluation and treatment, submit a sample to the state’s DNA database, and take any medications as ordered.

“I can’t stress enough the bravery and heroism of the survivor in this case,” Conley said. “It wasn’t limited to fighting back against her attacker. It included working with investigators and testifying in court. We’ve seen enough of these cases to know how painful and difficult that can be, but she found the strength to do it. Thanks to her, this predator can’t hurt another woman.”

After a week-long trial, a Suffolk Superior Court jury convicted Flavell yesterday of assault with intent to rape, assault and battery, and two counts of assault and battery with a dangerous weapon for the Oct. 22, 2009, attack on a 27-year-old female inside an MGH bathroom. The latter convictions reflect Flavell’s use of a wall and the floor to inflict injuries upon the woman.

At a second trial today, Assistant District Attorneys Tara Burdman and Mindy Klenoff of Conley’s Sexual Assault Unit proved that Flavell had previously been convicted of assault with intent to rape in 1998 for an incident in Methuen. As a repeat offender, Flavell became eligible for a longer sentence under Massachusetts law.

Anne Kelley-McCarthy was the victim-witness advocate assigned to the case. Flavell was represented by attorney Neil Madden.