Short answers, pulled from the story.
Jack Swigert was the first person aboard Apollo 13 to speak the words "Houston, we've had a problem here" after an oxygen tank ruptured in the service module. Commander Jim Lovell then repeated the statement. The crew aborted the lunar landing and returned safely to Earth on the 17th of April, 1970.
Swigert replaced command module pilot Ken Mattingly just three days before the 11th of April 1970 launch. The prime crew had been exposed to rubella through astronaut Charles Duke, and because Mattingly had no immunity to the disease, NASA moved Swigert into the seat to avoid the risk of illness during critical mission phases.
Swigert was removed from the Apollo-Soyuz crew after the 1972 Apollo 15 postal covers investigation revealed he had agreed to autograph philatelic items for West German stamp dealer Hermann Sieger in exchange for about $2,500. He initially denied involvement when questioned by NASA investigators. NASA Deputy Administrator George M. Low removed him from the mission following his admission.
The Apollo 13 crew traveled farther from Earth than any other astronauts up to that time, following a slingshot route around the Moon designed to return them safely after aborting the lunar landing. That distance record stood until the Artemis II lunar flyby in 2026.
Swigert won election to represent Colorado's 6th congressional district on the 2nd of November, 1982, with 64% of the vote, but he never served. He died of respiratory failure at Georgetown University Hospital's Lombardi Cancer Center on the 27th of December, 1982, seven days before his congressional term was set to begin. He was aged 51.
Jack Swigert is buried alongside his parents in Mount Olivet Cemetery in Wheat Ridge, Colorado. His funeral in Denver was a full military honors service attended by roughly a thousand mourners, including fifteen astronauts among them Jim Lovell and Fred Haise, and featured a missing man flyover by A-7 Corsairs of the Colorado Air National Guard.