Meanwhile, NFLPA executive director DeMaurice Smith will review the incident, The Denver Post reported.
Magid said he thought he got Dumervil's paperwork of his restructured contract that included a 2013 salary cut from $12 million to $8 million back to the team by the 4 p.m. ET deadline. The Broncos released Dumervil on Friday because the paperwork was not filed by the deadline.
Magid told USA Today Sports that Dumervil contacted him Saturday to say he wanted to move in another direction.
"It's terrible, but he said he knows what happened and why it happened," Magid told the newspaper.
Magid said he will waive his right as a fired agent to have Dumervil wait five days to hire a new agent. Thus, Dumervil's new agent can start working on getting him a new deal as soon as he hires one.
Dumervil is expected to hire CAA, a source told ESPN.
The Broncos asked the league office if it would honor the verbal agreement on the revised contract the team negotiated with Dumervil but the request was denied, according to the Denver newspaper. The paper reported that Smith will look into the matter because Dumervil may have been hurt most by the botched contract exchange.
Had the Broncos not released Dumervil before Friday's deadline, his $12 million salary for 2013 would have become guaranteed.
According to a source, both Dumervil's reps and the Broncos reached agreement at 3:25 p.m. ET on the restructured contract. But the team did not get a fax from Dumervil's agent until 4:06 p.m. ET, so it had to release him, according to the source.
Broncos team president John Elway issued a statement Friday night, explaining the situation from the team's point of view.
"Due to the procedural elements that were involved in executing the new proposal, we imposed a 1 p.m. MDT deadline for a decision, one hour before the NFL's waiver wire at 2 p.m. MDT. Our deadline was clearly communicated to Elvis' representative," Elway said in the statement. "At 1 p.m. MDT, we were informed by Elvis' representative that he declined our offer. We then prepared Elvis' termination notice to officially file his release with the NFL office.
"At approximately 1:25 p.m. MDT, however, we were informed that Elvis changed his mind and accepted the same contract we proposed nearly two-and-a-half hours earlier. Although we expressed our concern regarding the time constraints, we were assured that the signed documents would be submitted to us before the league's waiver deadline.
"We did not receive the documents from Elvis by the league's deadline and were forced to release him shortly before 2 p.m. MDT.
"Due to this situation, there are now salary-cap implications associated with this transaction that we must consider with regard to potentially re-signing Elvis. At this moment, we are discussing all of our free-agency options to determine what's best for the Denver Broncos."
Magid said he received the renegotiated document from the Broncos at 3:45 p.m. ET. He said he had Dumervil wait by a fax machine to receive the copy and then send it back.
Earlier Saturday, Magid said teams were interested in visiting with Dumervil after the NFL owners' meetings end in Arizona on Wednesday. The market could dry up.
Dumervil signed a six-year, $61.5 million contract in 2010 when Josh McDaniels was coaching the team and before Elway joined the Denver front office.
Dumervil had 11 sacks last season, second on the team behind Von Miller. Dumervil led the league with 17 sacks in 2009.
Though the parties had agreed on a deal, the odds of Dumervil returning to Denver are hampered because cutting him could leave them with a salary cap hit of up to nearly $5 million.
Information from ESPN NFL senior writer John Clayton, ESPN NFL Insider Adam Schefter, AFC West blogger Bill Williamson and The Associated Press was used in this report.