For more on this story, see CNN affiliate KTSU
(CNN) -- Elizabeth Smart stormed out of the courtroom Wednesday during the trial of Brian Mitchell, charged with kidnapping the Utah teenager in 2002, CNN affiliate KSTU reported.
Visibly upset, she left the courtroom during the testimony of a defense witness, Dr. Paul Whitehead, a forensic psychiatrist at the state mental hospital who treated Mitchell from 2005 to 2008.
Whitehead testified about Mitchell's desire to bear children with Smart, KSTU reported.
"Mr. Mitchell was talking with Ms. Smart about having babies to the point where Ms. Smart actually picked out a name in case that happened," Whitehead testified. That statement prompted Smart's departure. She was followed by her mother.
Mitchell's federal trial had been halted a day earlier when Mitchell suffered a medical problem in court.
On Tuesday, KSTU posted a picture of Mitchell on its website, showing him wearing an oxygen mask and sitting on a stretcher as he was being loaded into an ambulance.
Mitchell, as usual, had begun singing when he was led into the courtroom Tuesday: "O Holy Night," KSTU reported.
U.S. District Judge Dale Kimball began the proceedings by raising an issue in a note sent from jurors. As Kimball asked for jurors to be brought in, Mitchell began to wail and dropped to the floor, KSTU said. Defense attorney Wendy Lewis told Kimball, "He's having a seizure, your honor."
An ambulance was called, and paramedics came into the courthouse to examine Mitchell, according to KSTU.
"The judge told the jury that an issue had come up and the trial would be suspended," said Melodie Rydalch, a spokeswoman for the U.S. attorney's office in Utah.
Rebecca Woodridge, Mitchell's stepdaughter, told KSTU he has suffered seizures before. "He's had a few of them in the past year. I don't think there's any reason for him to fake this," she said.
Defense attorney Robert Steele said outside the courthouse that Smart herself had testified about Mitchell suffering a seizure during her time in captivity. "We watched a seizure," he said, according to KSTU. "It really happened."
Mitchell, 57, faces charges of kidnapping and unlawful transportation of a minor across state lines in Smart's abduction. Then 14, she was kidnapped from her bedroom in her family's Salt Lake City, Utah, home. Nine months later, she was found in the company of Mitchell -- a drifter and self-described "prophet" who called himself Immanuel -- and his wife, Wanda Barzee.
Mitchell's trial resumed Monday after taking last week off. Barzee earlier testified as a defense witness.
Defense attorneys are mounting an insanity defense for Mitchell, hoping to prove that mental illness clouded his mind to such a degree that he did not understand that his actions were wrong when he abducted and held Smart.
The defense said Tuesday in court that they plan to conclude their case late this week, perhaps Thursday. The prosecution said it has up to five days of rebuttal witnesses, but both sides assured Kimball that they would be finished with closing arguments by December 10.
CNN's Ashley Hayes and Michael Martinez and In Session's Jean Casarez contributed to this report.