ALBANY - Hiram Monserrate was sworn in Wednesday as a new state senator, despite facing charges that he slashed his girlfriend's face with a piece of broken glass in a jealous rage.

Monserrate, part of a new influx of lawmakers who helped Democrats gain control of the Senate for the first time in four decades, stood on the floor on the historic day and swore to uphold the federal and state constitutions and his office.

He was surrounded by a dozen applauding friends, relatives and staff, but his girlfriend was conspicuiously absent. Others said the charges should have kept Moserrate from taking office, and one senator turned away before a photo could be taken with the new lawmaker.

“I guess they were wrong. I'm here, and I'm here for the long haul,” Monserrate said of his critics. “Of course my colleagues are treating me nice,” he said.

Monserrate was charged with assault and weapon possession after Karla Giraldo's face was slashed on Dec. 19 at his Queens home. Both the former New York City councilman and Giraldo say the incident was an accident - Monserrate told police that he tripped while holding a glass of water and that the glass accidentally hit her.

But authorities say evidence, including surveillance videos, paints a more violent picture of a heated argument and a frightened, bleeding woman in distress. Investigators say Monserrate purposely smashed her face with broken glass because he thought she was also dating a police officer.

The videos come from several cameras in the apartment building. The first shows the two arguing and Monserrate throwing a policeman's union card down a garbage chute, according to a law enforcement official, speaking on the condition of anonymity because the investigation is ongoing.

The two return into the apartment, and the video catches them sometime later, Giraldo's face covered with a bloody towel. The official said it's believed Monserrate smashed the glass over furniture before hitting her with it. Investigators on Monday seized similar glasses from his home.

Monserrate is seen yanking Giraldo by the shoulder down the second-floor stairwell, according to the official who saw the video. Giraldo is crying, and pounding on a neighbor's door as he pulls her away, the official said. She drops the towel, which is later found on a stairwell. The two are then shown downstairs in a small vestibule, where Monserrate tries to pull Giraldo outside.

“She's holding on with two hands, like a kid who didn't want to leave his bike. She looks terrified,” the official said.

Giraldo went to the emergency room; the gash over her eye required 25 stitches. Doctors contacted Queens police and reported a woman was assaulted, the official said. According to the police report, Giraldo initially said she was assaulted, then changed her account after learning officers planned to arrest him. She later filed a statement with police saying she did not wish to press charges.

The Queens district attorney's office said the case is pending.

On Wednesday in Albany, Monserrate declined to discuss the allegations. Asked about the continued attention on whether he should be seated, he said, “That's politics.”

Senate Majority Leader Malcolm Smith said there was no legal reason to prevent Monserrate from being seated, and in the upcoming days “we will make some decisions about how we handle his actual role.”

Brooklyn Republican Sen. Martin Golden, who earlier introduced a resolution to delay Monserrate's swearing in for a month until the issue is resolved, accepted Monserrate's handshake but turned away before the press could take their picture together.

Golden told The Associated Press that the Queens Democrat should have been kept out of the seat Wednesday, and that the pending criminal case involved “an absolutely horrendous assault on a woman.”

“It definitely takes the institution down and we don't need that,” Golden said.

Monserrate, a council member since 2001, was elected to the Senate in November. If convicted of felony second-degree assault, he could face seven years in prison and the loss of his seat.