OAKLAND, Calif., Feb 1 (Reuters) - The widow of the gunman behind the deadliest mass shooting in modern U.S. history knew he was planning an attack and concocted a cover story for him, federal prosecutors said in a California court on Wednesday.

Prosecutors revealed new details about their case against Noor Salman, 30, as they argued she should remain jailed on charges stemming from the June 2016 shooting at a gay nightclub in Orlando, Florida.

U.S. Magistrate Judge Donna Ryu did not immediately rule, instead ordering psychiatric and psychological tests for Salman.

Related: See images from the tragic attack

20 PHOTOS Pulse nightclub shooting See Gallery Pulse nightclub shooting An aerial view shows the Pulse gay night club after a mass shooting in Orlando, Florida, U.S. June 12, 2016. REUTERS/Carlo Allegri Friends and family members embrace outside the Orlando Police Headquarters during the investigation of a shooting at the Pulse nightclub, where people were killed by a gunman, in Orlando, Florida, U.S June 12, 2016. REUTERS/Steve Nesius TPX IMAGES OF THE DAY Friends and family members embrace outside the Orlando Police Headquarters during the investigation of a shooting at the Pulse nightclub, where people were killed by a gunman, in Orlando, Florida, U.S June 12, 2016. REUTERS/Steve Nesius Friends and family members embrace outside the Orlando Police Headquarters during the investigation of a shooting at the Pulse nightclub, where people were killed by a gunman, in Orlando, Florida, U.S June 12, 2016. REUTERS/Steve Nesius ORLANDO, FL - JUNE 12: FBI agents investigate near the damaged rear wall of the Pulse Nightclub where Omar Mateen allegedly killed at least 50 people on June 12, 2016 in Orlando, Florida. The mass shooting killed at least 50 people and injuring 53 others in what is the deadliest mass shooting in the country's history. (Photo by Joe Raedle/Getty Images) ORLANDO, FL - JUNE 12: FBI agents investigate near the damaged rear wall of the Pulse Nightclub where Omar Mateen allegedly killed at least 50 people on June 12, 2016 in Orlando, Florida. The mass shooting killed at least 50 people and injuring 53 others in what is the deadliest mass shooting in the country's history. (Photo by Joe Raedle/Getty Images) ORLANDO, FL - JUNE 12: FBI agents investigate near the damaged rear wall of the Pulse Nightclub where Omar Mateen allegedly killed at least 50 people on June 12, 2016 in Orlando, Florida. The mass shooting killed at least 50 people and injuring 53 others in what is the deadliest mass shooting in the country's history. (Photo by Joe Raedle/Getty Images) Friends and family members embrace outside the Orlando Police Headquarters during the investigation of a shooting at the Pulse night club, where as many as 20 people have been injured after a gunman opened fire, in Orlando, Florida, U.S June 12, 2016. REUTERS/Steve Nesius TPX IMAGES OF THE DAY Demetrice Naulings sobs outside the Orlando Police Headquarters where police are interviewing witnesses in the investigation of a shooting at the Pulse nightclub, where people were killed by a gunman, in Orlando, Florida, U.S June 12, 2016. REUTERS/Steve Nesius Concerned friends and family of victims of the Pulse nightclub shooting wait outside of the Orlando Police Department on Sunday, June 12, 2016. (Joe Burbank/Orlando Sentinel/TNS via Getty Images) Ray Rivera, DJ at the Pulse nightclub, is consoled by a friend outside of the Orlando Police Department on Sunday, June 12, 2016. (Joe Burbank/Orlando Sentinel/TNS via Getty Images) Police stand in front of one of the houses that officials indicated was connected to the Orlando shooter in Port St. Lucie, Florida, U.S. June 12, 2016. REUTERS/Joe Skipper An aerial view shows the Pulse gay night club after a mass shooting in Orlando, Florida, U.S. June 12, 2016. REUTERS/Carlo Allegri Police stand in front of one of the houses that officials indicated was connected to the Orlando shooter in Port St. Lucie, Florida, U.S. June 12, 2016. REUTERS/Joe Skipper ORLANDO, FL - JUNE 12: FBI agents investigate near the damaged rear wall of the Pulse Nightclub where Omar Mateen allegedly killed at least 50 people on June 12, 2016 in Orlando, Florida. The mass shooting killed at least 50 people and injuring 53 others in what is the deadliest mass shooting in the country's history. (Photo by Joe Raedle/Getty Images) ORLANDO, FL - JUNE 12: FBI agents investigate near the damaged rear wall of the Pulse Nightclub where Omar Mateen allegedly killed at least 50 people on June 12, 2016 in Orlando, Florida. The mass shooting killed at least 50 people and injuring 53 others in what is the deadliest mass shooting in the country's history. (Photo by Joe Raedle/Getty Images) Officers arrive at the Orlando Police Headquarters during the investigation of a shooting at the Pulse nightclub, where people were killed by a gunman, in Orlando, Florida, U.S June 12, 2016. REUTERS/Steve Nesius An aerial view shows the Pulse gay night club after a mass shooting in Orlando, Florida, U.S. June 12, 2016. REUTERS/Carlo Allegri Orlando Police Chief John Mina and other city officials answer the media's questions about the Pulse nightclub shooting in Orlando, Florida June 12, 2016. REUTERS/Kevin Kolczynski Police lock down Orange Avenue around Pulse nightclub, where people were killed by a gunman in a shooting rampage in Orlando, Florida June 12, 2016. REUTERS/Kevin Kolczynski Up Next See Gallery Discover More Like This HIDE CAPTION SHOW CAPTION of SEE ALL BACK TO SLIDE

Salman was arrested earlier this month in the San Francisco Bay Area on federal charges of obstructing justice and aiding her late husband, Omar Mateen, in his attempt to provide material support to a terrorist organization.

She admitted knowing Mateen left their house with a firearm and a backpack full of ammunition before the Pulse nightclub shooting, Assistant U.S. Attorney Sara Sweeney told a federal judge in Oakland.

Sweeney also said Salman devised a cover story, directing Mateen to tell his parents, if asked, that he was at dinner with a friend.

"Noor aided and abetted her husband and repeatedly lied to the government," Sweeney said, calling her a "very calculating and callous person" who should be detained until her trial in Florida.

"Salman knew her husband was leaving to commit an attack and her actions contributed to the deaths of 49 people," she added.

Sweeney also alleged Salman accompanied Mateen on "casing" trips to two other locations, including Downtown Disney in Orlando, in the days before the shooting.

The prosecutor said Mateen asked Salman whether she thought people would be more upset by an attack on Downtown Disney or a club. Sweeney did not say whether Salman answered or specify her role in those trips.

Defense attorney Charles Swift said Salman's alleged admissions occurred after 18 hours in police custody, during which she was interrogated without a lawyer. Prosecutors have yet to provide written or recorded evidence of Salman's alleged admissions, Swift noted.

"She's alive and Omar Mateen is dead. So she's the only person they can charge," said Swift, describing Salman as a battered spouse who had learning disabilities in high school.

Salman's attorneys want her released to her family, saying she poses no threat to the public and requires mental health services not available in jail. They said she was asleep at home with the couple's 3-year-old son during the attack. (Reporting by Curtis Skinner in San Francisco; Editing by Colleen Jenkins and Phil Berlowitz)