Nadezya Ostapchuk consumed food that was mixed with steroid

The Belarusian shot putter Nadezya Ostapchuk received the gold medal at the 2012 London Olympics. But she tested positive for a steroid. As a result, she lost the medal that was given to Valeria Adams of New Zealand.
Two tests manifested that a steroid’s metabolites presented in her urine samples.
When an athlete is caught applying any banned medications, he/she is usually sentenced to a ban of two years. As for this Belarusian shot putter, she received one-year ban. Why was the sentence lighter? There were some circumstances which proved the following condition: the Belarusian shot putter didn’t use any prohibited preparation knowingly.
At the beginning Nadezya Ostapchuk blamed his former coach. She said that he had sabotaged her sample.
The Belarusian National Anti-Doping Agency examined this case. The International Association of Athletic Federation also participated in the investigation. It was found out that Yefimov was guilty. This person added powder of methenolone into food of Nadezya Ostapchuk during the last week before the 2012 Summer Olympics. The coach reported that he had worried about Nadezya Ostapchuk. He believed that this steroid would help to win.
In fact, it is difficult to define why Yefimov has done it. He only made the things worse.
Anti-doping agencies accepted these arguments. That’s why Nadezya Ostapchuk was sentenced just to one-year suspension.
As for supporters of Valeria Adams, they didn’t believe that Nadezya Ostapchuk had not applied the steroid knowingly. They affirmed that Yefimov just tried to protect the athlete. They confirmed that Nadezya Ostapchuk had taken steroids under recommendations of her coach.
If the Belarusian shot putter’s performance was amazing certain months before the 2012 Summer Olympics, her coach had to be sure that she would win. Why did he worry about her performance?