After Yusuf Zuck finished talking to Ember Vance on the phone, he didn't immediately go to Haidian but instead left the hospital room and went to Jade Cooke's room.
Before he had the altercation with Fleur Carson that night, he had left from Jade Cooke's room, and in less than two hours, he had returned to the hospital.
Hence, he needed to secure his alibis in advance, which included Jade Cooke and her siblings, the young nurse Paisley Kirk, and his father Felix Zuck—all credible witnesses.
Naturally, he couldn't say anything explicitly. He did not disclose to Jade Cooke that he had been summoned; he merely made a symbolic visit to Jade's room and exchanged a few words.
After leaving, he went back to Felix Zuck's room. Nurse Paisley Kirk had gone out to fetch some hot water, so he quietly informed his father about the police summons.
"Was it you who killed him?" Felix Zuck asked anxiously.
"No, how could I kill someone?" Yusuf shook his head.