Swann, 24, is a former fifth-round pick of the Saints back in 2015. He was in the third year of his four-year, $2.464 million contract and set to make a base salary of $615,000 for the 2017 season when the Saints waived him coming out of the preseason.
In 2016, Swann appeared in seven games for the Saints and recorded 22 tackles, no interceptions and four pass defenses.
Killings, 22, signed on with the Patriots as an undrafted free agent out of Central Florida back in May. New England elected to waive him as they trimmed their roster down to the 53-man limit, but was placed on the injured reserve after passing through waivers unclaimed.
New England elected to release him from their injured reserve with an injury settlement.
During his four-year college career, Killings recorded 99 total tackles, eight tackles for loss, one sack, five interceptions, 17 pass defenses, one forced fumble, and scored one defensive touchdown.