LOS ANGELES — One woman ran into Harvey Weinstein at a Hollywood film festival in February 2013. Later that night, he showed up at her hotel room, gained entry and raped her, she said. He threatened her life, she told the authorities.

A day later, Mr. Weinstein met the second woman at a hotel restaurant in West Los Angeles and invited her and another woman up to his room. There, he trapped her in a bathroom, grabbed her breasts and masturbated, prosecutors said.

Those two allegations were contained in a criminal complaint released in Los Angeles on one of the most remarkable days since revelations about the movie producer’s sexual harassment of women set in motion the global #MeToo movement.

Only hours before prosecutors in Los Angeles unveiled the new case against Mr. Weinstein, he had hobbled with a walker into a courtroom in Manhattan for a hearing on the eve of his long-anticipated rape trial there. Jury selection was to begin on Tuesday.

Now, however, even if Mr. Weinstein prevails in Manhattan, he will face a second trial in Los Angeles.

Neither woman in the Los Angeles case has been publicly identified. The first victim, an Italian model and actress, has said that she encountered Mr. Weinstein at a film festival and was shocked when he showed up at her door at the Mr. C luxury hotel in Beverly Hills.

“He grabbed me by the hair and forced me to do something I did not want to do,” she told the Los Angeles Times in 2017. “He then dragged me to the bathroom and forcibly raped me.”

About a day later, Mr. Weinstein victimized another woman he had arranged to meet to discuss a business matter at a Beverly Hills hotel, prosecutors said. The two spoke briefly before the woman and her acquaintance accompanied Mr. Weinstein to his hotel suite, according to the criminal complaint.

Prosecutors said the woman followed the producer into the hotel bathroom and, once inside, the female acquaintance shut the door behind her. She was unable to open it. Mr. Weinstein then took off his clothes, showered and held her in place by her breasts as he masturbated and then ejaculated onto the floor, the complaint said. It remained unclear in court documents what happened to the woman’s acquaintance.

The Los Angeles County district attorney, Jackie Lacey, said Mr. Weinstein has been charged with one felony count each of forcible rape, forcible oral copulation, sexual penetration by use of force and sexual battery by restraint. He faces up to 28 years in prison if convicted.

“We believe the evidence will show that the defendant used his power and influence to gain access to his victims and then commit violent crimes against them,” Ms. Lacey said in a statement.

There is some overlap between the New York and Los Angeles prosecutions. One of the victims in the Los Angeles case will also be called as a witness in New York to recount her experience with Mr. Weinstein in an effort to establish a pattern of behavior, prosecutors in Los Angeles said.

Mr. Weinstein’s lawyers declined to comment on the latest charges.

Though the authorities in Los Angeles could issue a warrant for Mr. Weinstein’s arrest, it was highly unlikely they would disrupt the trial in New York by seeking his removal to California, or that the judge in New York would allow it.

Still, defense lawyers said that the charges in Los Angeles could make it even harder to find an impartial jury in New York than it already was, as potential jurors are likely to see news accounts of the new allegations.

“If you’re Weinstein’s lawyers, this is another headache to deal with,” said Mark Bederow, a defense lawyer. “It’s all over the news. How are jurors supposed to ignore it?”

The importance of the New York trial to many of Mr. Weinstein’s accusers and their sympathizers was clear on Monday, as protesters gathered outside the State Supreme Court in Manhattan on a damp day. Some held signs with slogans like “justice for survivors” and “coercion is not consent.”

More than 80 women, including a number of prominent actresses, have come forward to accuse Mr. Weinstein of sexual misconduct, from unwanted touching and harassment to outright sexual assault. Most of those complaints, however, have not led to criminal charges, and many of his accusers are looking to the trial in New York to see if the criminal justice system can provide what they see as justice.

Rose McGowan, an actress who has accused Mr. Weinstein of sexual assault, said at a news conference in Foley Square that the trial in Manhattan marked “a moment of justice” for his accusers, even those who “won’t have even one day in court.” Addressing the disgraced producer she said, “You brought this on yourself by hurting so many.”

Another actress, Sarah Ann Masse, said, “As a group we have been threatened, bullied, intimidated and retaliated against.” then added, “we will not be silenced anymore.”

Inside the courthouse, the gallery of Part 99 of the State Supreme Court was packed with reporters and spectators, as Mr. Weinstein, 67, once one of the most powerful producers in Hollywood, made his way slowly to the defense table.

Over the next hour, Justice James M. Burke dealt a blow to Mr. Weinstein’s defense, ruling that it could not call as a witness the detective who was accused of withholding from prosecutors evidence that was favorable to the defense.

Mr. Weinstein’s lawyers had hoped to call the detective, Nicholas DiGaudio, as part of an effort to cast doubt on the New York Police Department’s investigation of Mr. Weinstein.

Detective DiGaudio’s handling of the evidence became an issue in October 2018, when one of the charges in the indictment related to a former actress was thrown out by Justice Burke. The actress, Lucia Evans, had accused Mr. Weinstein of forcing her to perform oral sex on him during a business meeting.

Prosecutors said Detective DiGaudio had failed to inform them that Ms. Evans had given a different version of the story to a friend, saying she had willingly agreed to the sex act after Mr. Weinstein promised her acting jobs in return. Ms. Evans has said that she had never consented, and Detective DiGaudio has denied withholding information from the prosecutors.

Jury selection in the trial will begin on Tuesday. The lawyers will pick 12 jurors and six alternates from a pool of 500 New Yorkers.

In New York, Mr. Weinstein is charged with raping one woman, who has not been identified in court documents, at a Midtown Manhattan hotel in March 2013 and forcing oral sex on a second woman, Mimi Haleyi, a production assistant, at his Manhattan apartment in 2006.

Mr. Weinstein maintains that his sexual encounters with the women were consensual.

The producer also faces a charge of predatory sexual assault for committing a serious sex crime against more than one person. If convicted of that charge, Mr. Weinstein faces a maximum of life in prison.

To further buttress that charge, prosecutors plan on calling “The Sopranos” actress Annabella Sciorra to testify against Mr. Weinstein who she said sexually assaulted her in 1993 in her Gramercy Park apartment.

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Credit…Gabriela Bhaskar for The New York Times

The Manhattan district attorney’s office has also won permission to call three other women, who have yet to be identified, to testify about their allegations of sexual assault by the producer. Prosecutors hope those witnesses will help convince a jury that Mr. Weinstein has long been a sexual predator, supporting the claims of the two main accusers.

Prosecutors in Pennsylvania used a similar strategy in the sexual assault trial of the comedian Bill Cosby, who is in prison.

The Italian model-actress spoke to authorities in October 2017, according to her attorney, Dave Ring, shortly after The New York Times first reported on the sexual abuse allegations against Mr. Weinstein.

“The last two years have been a real roller coaster ride for her, because it’s taken two years to get to this point, and she wasn’t sure they were going to get there,” Mr. Ring said in a telephone interview.

During her encounter with Mr. Weinstein in 2013, he showed up in the lobby of her hotel and came up to her room uninvited, she told the Los Angeles Times in 2017.

According to the criminal complaint, Mr. Weinstein forced oral sex on her, then intercourse. “It was the most demeaning thing ever done to me by far,” she said in the 2017 interview with The Los Angeles Times. “He made me feel like an object, like nothing, with all his power.”

William K. Rashbaum and Jodi Kantor contributed reporting.