Futures deals are essentially camp invites that will give players the opportunity to compete for roster spots during offseason workouts and training camp.
Mack, 22, is a former seventh-round pick of the Saints back in May of last year. He agreed to a four-year, $2.6 million contract, but was waived coming out of the preseason.
Mack later signed on to the Saints’ practice squad and had a brief stint with the Steelers before Chiefs added him to their taxi squad in November.
During his college career at Notre Dame, Mack caught 68 passes for 716 yards receiving and four touchdowns over the course of 24 games.
Marshall, 22, wound up going undrafted out of James Madison in May of last year. He later signed a three-year, $1.755 million contract with the Chiefs, but was waived at the start of the regular season.
The Chiefs later signed Marshall to their practice squad after clearing waivers, but he was eventually released a month later.