An attorney representing Dez Bryant has sent David Wells, the wide receiver's longtime adviser, a cease-and-desist letter to end their formal business relationship, Wells told ESPNDallas.com.

The letter, sent in late February by Jordan Siev, a New York City-based attorney for Reed Smith, also reiterated a prior termination of power of attorney by Bryant. Wells said he had used the power of attorney to handle some of Bryant's affairs the past few years.

The dispute between Bryant and Wells is among the reasons the star receiver has yet to reach a long-term deal with the Cowboys.

The disagreement between those representing Dez Bryant and his longtime adviser could muddy long-term contract talks between the star receiver and the Cowboys. AP Photo/Richard Lipski

In March, the team placed the franchise tag on Bryant that will pay him nearly $13 million this season, but the receiver has yet to sign it. The Cowboys want Wells to remain closely involved with Bryant, whether it's providing security when he goes out to clubs or in handling some of his day-to-day responsibilities so the receiver can focus on football.

When reached by ESPNDallas.com, Siev acknowledged the letter but declined any further comment.

Bryant could not be reached for comment. The Cowboys declined to comment.

Wells said the legal maneuvering did not faze him and he would not turn over any documents regarding any aspect of his relationship with Bryant, as the letters from Siev also requested.

Wells says he has an adviser agreement with Bryant that runs through 2016 but would consider terminating the contract if Bryant's attorneys pay off the remaining amount he is owed.

Wells and Bryant have a complex relationship that is both business and personal. They still talk frequently, and Bryant stopped by his home briefly to chat Wednesday.

Wells has played a role in Bryant getting marketing deals with BioSteele Sports Supplements and the Jordan Brand. Bryant, according to his new agency, wants those types of arrangements to stop; they want to handle all of his marketing deals.

The relationship between Bryant and Wells goes back to 2009, when Wells began mentoring Bryant after the receiver was suspended for Oklahoma State's 2009 season for lying to the NCAA. The Cowboys then drafted Bryant in April 2010.

Bryant lived in Wells' home from 2010 to '12 before moving into a rental house less than a mile from Wells' current residence.

"I don't go out to the club and hang with Dez," Wells said. "That ain't my job.

"My job is to make sure Dez is productive in society and do what he's supposed to do to make him a better citizen, so he can be a productive player for the Dallas Cowboys."

Bryant, who caught 88 passes for 1,320 yards and 16 touchdowns last season, switched agents from Eugene Parker to Roc Nation in November. Agent Tom Condon is currently handling contract negotiations between Bryant and the Cowboys for Roc Nation. Bryant has said he wants more control over his career.

Wells, a crisis management expert, has spent nearly three decades as a private investigator. In the past, he has provided security for former Cowboys players Michael Irvin and Adam Jones. He also has worked with Josh Brent since his 2012 car accident that killed practice squad linebacker Jerry Brown. Brent, charged with intoxication manslaughter, spent nearly six months in jail. He returned to the Cowboys last season and is expected to make the team this year.

The Cowboys implemented the "Dez Rules" in the summer of 2012, after an incident involving his mother led to a misdemeanor family assault charge that was ultimately dismissed. Wells helped enforced those rules, which ranged from not drinking alcohol to not being out past midnight.