UPDATE (Wednesday, 10:15 a.m.):

While the NFL has the latitude to add another 10 games on top of Gregory's current four-game suspension, that won't necessarily happen. The reason: The purpose of the program is to rehabilitate, not punish. If there are indications that Gregory, despite his struggles, is seriously addressing his addiction, adding six games to bring the suspension to 10 is more likely.

Original story (Tuesday):

Randy Gregory's struggles with addiction have landed him in a drug treatment facility and will extend a four-game suspension that is already in place, multiple sources said.

The defensive end has failed a fifth test -- his fourth while a member of the Cowboys -- and will not report to training camp in Southern California with his teammates Thursday. He's now at an undisclosed facility, sources confirmed, and it's unclear if he'll participate in any part of training camp.

Gregory's return to the field is equally uncertain.

The player was hit with a four-game suspension earlier this year that still allowed him to take part in training camp and preseason games. One source said Gregory checked himself into a treatment facility earlier this month in the hopes of completing the program before camp starts later this week. But that same source said that Gregory left the facility for a weekend and missed a scheduled test.

In this stage of the NFL's substance-abuse program, a missed test carries the same weight as a failed test. That would increase the suspension to 10 games.

Defensive end DeMarcus Lawrence (four games) and linebacker Rolando McClain (10 games) also are suspended to open the season. If Gregory's punishment is increased, it would mean the defensive side of the ball could lose up to a minimum of 24 games from those three key contributors.

Cowboys coach Jason Garrett, attending a coach's clinic in Arlington on Tuesday afternoon, declined to answer any questions about Gregory's status.

"I don't want to comment on that,'' Garrett said. "I'm not commenting on Randy Gregory.''

Gregory tested positive for marijuana in February 2015 at the NFL scouting combine and entered the league in the first stage of its substance-abuse program. He tested positive for marijuana twice at Nebraska, in January and April 2014, and was told he would be kicked off the team if he failed a third time.

The revelation led to Gregory, who was considered among the draft's top 10 players, to slide. In the days leading up to the draft, Cowboys officials determined they would not take Gregory in the first round but did not remove him from their board as some teams had reportedly done around the league.

Gregory told the Cowboys that he first began to smoke marijuana after high school, before he left for college, as a way to cope. Cowboys owner Jerry Jones was struck by the openness the young player displayed in acknowledging his struggles during their conversations.

"I'm not going to go too far into what he thinks,'' Jones said hours after drafting Gregory in the second round 15 months ago. "But there is no question in my mind he is very aware and wants to do better and wants help.''

Gregory was outstanding in last year's training camp and got off to a fast start in the regular-season opener against the New York Giants, but suffered a high ankle sprain in the third quarter of that game that forced him to miss the next four weeks.

He wasn't nearly as effective when he returned. Gregory failed to record a sack in his rookie season but did record 16 quarterback pressures -- fourth on the team -- in limited duty. He had only 11 tackles.

Benson Mayowa, a veteran free agent signed by the Cowboys during the offseason, fourth-round pick Charles Tapper and second-year pro David Irving will be among those competing for the two open jobs at defensive end heading into training camp. The uncertainty surrounding Gregory also could lead to the club into giving a second look at veteran Dwight Freeney.

The league announced earlier this year that Gregory would be suspended for the first four games of this season, a penalty that will take a little more than $143,000 out of his pocket and could threaten another $370,000 he has in guaranteed money. That suspension meant Gregory had failed four tests -- three while a member of the Cowboys -- within the last year.

He's now up to five.

Two days after the four-game suspension became public, Cowboys executive vice president Stephen Jones issued a statement that read: "This is a disappointment. We've been clear with Randy about what his responsibilities are and what is expected of him. This is something he's going to have to work through and correct."

It has not been corrected. Gregory's inability to do so leaves his season in doubt and puts the Cowboys' defensive line in an even bigger bind.

Twitter: @DavidMooreDMN

Get the latest Cowboys news here | Follow dmn_cowboys on Twitter | Like our Cowboys Facebook page here