Suffolk County District Attorney Daniel F. Conley announced the conviction today of a repeat sex offender on charges that he attacked and tried to rape a woman at Massachusetts General Hospital last year.

A Suffolk Superior Court jury on its second day of deliberations found DAVID C. FLAVELL (D.O.B. 6/22/69) guilty 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.

“The woman he attacked showed tremendous courage, not just in fighting back but just as importantly in taking the stand to testify against him,” Conley said. “It couldn’t have been easy, but it was that courage that helped take this predator off the street.”

Because Flavell had previously been convicted of assault to rape, Suffolk prosecutors indicted that charge as a second or subsequent offense. Before he can be sentenced, prosecutors must prove that he is the same David C. Flavell convicted of the crime in Essex County in 1998. Those proceedings will take place in a jury-waived trial before Judge Charles T. Spurlock in courtroom 808 of Suffolk Superior Court tomorrow morning at 11:00.

Assault with intent to rape as a first offense carries a maximum term of 20 years in prison. As a second or subsequent offense, it carries a potential life sentence.

“We expect to seek a sentence appropriate to the facts of the case and the defendant’s criminal history,” Conley said.

During the week-long trial, Assistant District Attorney Tara Burdman and Assistant District Attorney Mindy Klenoff of Conley’s Sexual Assault Unit proved that Flavell waited for hours outside a women’s restroom on the first floor of the hospital, turning women away until the victim entered at about 3:00.

At that time, the evidence showed, he adjusted an “Out of Order” sign he had earlier placed on the door and entered after her. Once inside, Flavell tackled her, struck her head against the wall and floor, and tried to rape her.

The woman fought back, screamed, and resisted, however, and Flavell tried to walk away. The defendant exited the bathroom and tried to walk away from the area into the crowded hallway. An MGH security guard alerted to the assailant’s location immediately detained him. Hospital personnel observed that Flavell’s pants zipper was down and that he had blood on his shirt and pants. They brought him to a secure area where the victim was able to identify him as her attacker.

Boston Police sexual assault detectives responded to the hospital to seal the crime scene and interview the victim. Detectives observed blood on the floor and walls of the women’s bathroom, as well as buttons from the victim’s pants on the floor. Police also located and seized the handwritten sign that had been taped to the door.

The victim, who sustained serious but not life-threatening injuries, was escorted to the hospital’s emergency room for examination and treatment.

Flavell is represented by attorney Neil Madden. Anne Kelley-McCarthy is the victim-witness advocate.