(CNN) -- Interim Egyptian President Adly Mansour sent a letter to the family of jailed Al Jazeera journalist Mohamed Fahmy on Sunday telling him that Fahmy "will enjoy all his rights guaranteed by Egyptian law."
Mansour also ordered Egypt's interior minister to follow up on Fahmy's health condition and "to provide all possible care."
Fahmy, a former CNN producer, injured his shoulder before his arrest in December while working as bureau chief for Al Jazeera English in Cairo. He's complained about not getting proper medical treatment while in prison. He says that because of the lack of treatment, he no longer has full use of his right arm.
On Saturday, Fahmy, escorted by heavily armed, balaclava-wearing guards, arrived at a civilian hospital for the first time for a shoulder scan. Friends and family talked to him through the steel mesh of a prisoner transport vehicle before he was taken inside, where they had more access.
The visit by family and friends "put him in a good mood," said Fahmy's fiancee, Marwa Abdel Magid. "It's the first time I've seen him smile since he got arrested."
Fahmy, who was seen barely able to lift his arm during his examination, had MRI and CT scans at the hospital.
He said he and his colleagues -- Al Jazeera correspondent Peter Greste and producer Baher Mohamed -- were in good spirits. They also now receive daily newspapers to alleviate the boredom while they wait for their trial to end.
Fahmy said he wanted more time outside his windowless cell with his colleagues. He also wants his case resolved faster and more time with his lawyer than the 45 minutes he receives before each session.
In the letter, the interim President promised to "make sure the case is resolved quickly and that justice is achieved according to the law."
Fahmy, Greste and Mohamed have been detained for almost three months after security services raided their workspace at the Marriott hotel. The Egyptian government says they distorted their coverage in favor of ousted President Mohamed Morsy and the Muslim Brotherhood, which is designated a terrorist group in Egypt.
They are on trial, charged with spreading false news and belonging to a terrorist organization, which Al Jazeera strongly denies. The case has been widely condemned internationally as an attack on free speech. Their trial will resume on March 31.