Major League Baseball is expected to announce in the next few days that another player has tested positive for the steroid Turinabol, a drug that was commonly used by East German athletes in the 1970s. The positive test is one of a handful being processed, two sources familiar with the cases told Outside the Lines, meaning it's all but certain that more announcements will follow.

Turinabol, whose chemical compound is dehydrochlormethyltestosterone (DHCMT), is not something that would likely be found in the tool kit of a modern PED guru. But it is showing up widely again: Toronto Blue Jays' Chris Colabello and the Philadelphia Phillies' Daniel Stumpf were suspended after traces of Turinabol were found in their systems. The two, along with the player to be named, tested positive during spring training. St. Louis Cardinals catcher Cody Stanley was suspended in September after he tested positive for the drug.

MLB officials are examining what connections might exist between the players to explain Turinabol's apparent resurgence but have not found any so far, a source told Outside the Lines. But two possible explanations exist for why positive tests are spiking, sources said: better testing technology and/or a supplement taken by athletes.

Testing for Turinabol took a major leap forward two years ago, and as anti-doping labs have adopted the technology, users apparently didn't get the word. Any drug someone takes breaks down into metabolites, a residue of the drug that can stay in the system long after the original or parent drug has cleared. Turinabol, like most oral steroids, breaks down relatively quickly in the body and used to be undetectable after a week, and sometimes even less time. But two years ago, researchers found that by increasing the sensitivity of their testing equipment, they could detect some metabolites that stayed in the body much longer.

"The window of detection has moved out to, typically, several weeks, and in some rare circumstances up to months after administration," said Daniel Eichner, the president of the Sports Medicine Research and Testing Laboratory in Utah, which works with most major sports leagues.

As a result, players who might have used it without detection for years are finding themselves suddenly vulnerable to testing.

"That's what makes the most sense," one source close to MLB's testing program said. "There really isn't another theory right now."

The updated testing also could help explain why the recent positive tests turned up in spring training, which seemed odd to anti-doping experts. Players know they'll be tested in spring training, so it's rare for a player to have anything in his system when he reports to camp. Because testers found a metabolite of the drug and not the parent drug itself, they know those players probably used Turinabol more than a week before they were tested. The players have all denied knowingly taking the drug, but if their use was intentional, it would make sense that they stopped more than a week before reporting, with the belief that the drug had cleared their systems.

The unnamed players who tested positive have been informed, and MLB officials are still wrapping up the administrative process required to suspend them. Sources did not say when the players tested positive or how many are on major league rosters, but anyone on a team's 40-man roster has the right to appeal, which can delay a suspension by several weeks.

Besides the improved testing, there is another possible culprit for the recent spike in Turinabol positives, though sources told Outside the Lines it's a bit more speculative.

The supplement Alpha-4D, sold by Shredded Labs, includes an oral form of Turinabol. None of the players who tested positive has said he used the product, but it was placed on the U.S. Anti-Doping Agency's "high risk" supplement list in March 2014 and is the one over-the-counter product that has been identified by the agency as containing the drug. The supplement is advertised as a "pro-anabolic stack," which should be a flashing neon warning sign to any athlete who is subject to testing. Such products are often laced with banned drugs, whether those drugs are listed in the ingredients or not. Players are warned from the beginning of their careers that they should only take supplements preapproved by MLB and that they are liable for anything that shows up in their bodies.

MLB officials declined to comment on the recent tests, citing the program's confidentiality. Major League Baseball Players Association executive director Tony Clark did not return a message seeking comment.