SAN FRANCISCO (AP) — A former city health commissioner who allegedly lied to an ex-boyfriend about his HIV status is the first person charged under a state law against intentionally exposing another person to the virus, prosecutors said.

Ronald Gene Hill, 46, was arrested in Grass Valley, 50 miles northeast of Sacramento, following his indictment by a grand jury, said Mark MacNamara, spokesman for the San Francisco district attorney’s office.

It’s the first arrest under a 1998 state law making it a crime to knowingly and intentionally expose another person to the virus that causes AIDS.

“Because this is the first case to be tried of its kind, it presents many difficulties, but the evidence to the grand jury was compelling enough to indict him,” MacNamara said.

In March 2002, a San Francisco judge imposed a $5 million default judgment against Hill — $2.5 million in damages and $2.5 million in punitive damages — to be awarded to Hill’s former lover, Thomas Lister.

Baron Drexel, the lawyer who represented Lister in his civil suit, said that prosecutors originally were unwilling to bring criminal charges against Hill, who was arrested.

“People lie to each other,” Drexel said. “But when it comes to an issue like this, it’s not justifiable at any level.”

Drexel said Lister had been dating the former health commissioner for about five months and the couple were taking an Alaskan cruise together in July 2000 when he discovered medical records indicating Hill was taking medication for HIV.

The two earlier had discussed their negative HIV status and both agreed to get tested before having sex, Drexel said. Hill told Lister he tested negative.

On the cruise, Lister suffered chills and fever. One of the ship’s medical staff asked both men whether they had been tested for HIV. Both said they were negative.

After the trip, Lister tested positive, Drexel said. He sued in January 2001.

Hill, who served on the commission from 1997 to 2000, disappeared during the civil trial and Lister never received any money, Drexel said.