Nogales, Mexico (CNN) -- In the push to free an American woman from a Mexican prison, a video shown in court Thursday could be key.
The security camera footage shows Yanira Maldonado and her husband boarding a bus in Mexico last week. They are carrying a purse, two blankets and two bottles of water.
It's an everyday scene that plays out at bus stations around the world. But in this case, defense attorney Francisco Benitez argues that the images are a crucial piece of evidence.
Why? Because nothing they're carrying, he argues, could hold the amount of marijuana that Yanira Maldonado is accused of smuggling.
Maldonado, a Mormon mother of seven, has been in a Mexican jail for more than a week. Authorities accuse her of trying to smuggle 12 pounds of marijuana under a bus seat. She has maintained her innocence, and the case has drawn widespread media coverage and attention from U.S. lawmakers as family members push for her freedom.
The revelation of the video comes at a key juncture in the case. A Mexican judge must decide by Friday whether there's enough evidence to charge Maldonado with drug trafficking. If she's not charged, Maldonado must be released, Benitez said.
The video footage shown in court Thursday suggests that someone else brought the marijuana aboard the bus, the lawyer said.
The packages of marijuana allegedly recovered from under Maldonado's seat would not have fit in her purse, Benitez said.
Maldonado's attorneys also presented documents that show that she and her husband, Gary, have no criminal records in the United States, Benitez said.
Word that the surveillance video had been shown in court was a big relief, Gary Maldonado told reporters Thursday night.
"That was the key that would help us prove her innocence," he said.
Prosecutors' efforts to say the drugs could be hidden inside the blankets won't win the day, he said.
"It showed right on the film clear as day there's no way you could carry 12 pounds or 5.7 kilos with one arm. You could see me fold the blankets curled up," he said.
The Mexican military officials who arrested Maldonado haven't made their case yet in court. The soldiers were scheduled to appear Wednesday but didn't show.
Maldonado's family denies the charges and are optimistic the case against her is crumbling.
Mexican authorities arrested Maldonado on May 22 as she and her husband were on their way back to Arizona.
Gary Maldonado said he believes Mexican soldiers at the checkpoint wanted a bribe. A Mexican state official also told CNN it appears that Maldonado was framed.
A regional office of Mexico's defense ministry said troops conducting a routine investigation stopped the bus Maldonado was riding in and found 12.5 pounds (5.7 kilograms) of a substance that appeared to be marijuana under her seat.
Troops turned the case over to the Mexican attorney general's office, the defense ministry said. Maldonado is being housed in a women's prison in Nogales while authorities decide her fate.
In an interview Wednesday with CNN, Maldonado said she has been turning to Scripture to survive the ordeal.
"Reading the Scriptures, reading the Book of Mormon, praying, fasting," Maldonado said. "And all the support that I've been getting from my family, my husband, my children and everybody out there reaching out to help."
Family members' tearful pleas for her release have drawn widespread media attention to the case and caught the attention of U.S. officials.
"I am watching this very, very closely," said Rep. Matt Salmon, R-Arizona. "After the hearing tomorrow, if I have concerns, I may end up having to go to Mexico myself and get involved in this thing personally."
Salmon said he's spoken about the case with the U.S. ambassador to Mexico and Mexico's ambassador in Washington.
"This case gets stranger by the minute," Salmon said, "and I think most Americans as they've been watching it unfold have a lot of concerns."
Salmon said witnesses' testimony that Maldonado was only carrying a purse when she got on the bus is among the details that caught his attention.
"What concerns me more than anything is that I want to make sure justice is met. I want to make sure that she is treated with every courtesy and fairness that we would expect in our own judicial system," he said.
State Department officials said consular officials met with Maldonado Wednesday and last Friday, and are in regular contact by phone.
U.S. diplomats are doing the same things they usually would when a U.S. citizen is arrested in a foreign country, but maybe to a higher degree because of the high-profile nature of the case, a senior administration official said.
On Thursday night, Gary Maldonado said his wife was in good spirits.
"She was in a good mood," he said. "She feels like she was going to get out, since we have the evidence that proves her innocence."
CNN's Christine Theodorou, Casey Wian, Elise Labott and Catherine E. Shoichet contributed to this report.