Flashback...
The day Eduardo got kidnapped by Luca, Marcello was at the hotel with Mr Rossi. He never expected his visit, but he came to make a deal with Marcello.
"If you want these files, you'll have to agree to my conditions", was what he said.
"Let's hear it. These conditions of yours" Marcello replied.
Mr Rossi was silent for a few seconds. He was collecting his thoughts before speaking. This wasn't what he wanted to do, but he had to do it.
"...." Without hesitation, he said everything he had to to Marcello.
He revealed how he worked for Lady Ivanov. There are a lot of families, working for her. They believed her husband, who was the famous Mafia boss of Russia, was going to die soon and she'd take over with her son.
Everyone wanted to be on good terms with her. They did everything Lady Ivanov asked, and the Rossi household was one of them.