Because Mohammed is an American citizen who was only on holiday in the West Bank when he was arrested, his case has attracted the attention of US lawmakers.
"This is a case where the US does have influence. It's just failing to exercise its influence, and that's a great dereliction of duty," says Democratic US Senator, Chris van Hollen, from his office in Washington DC.
Along with 26 other US lawmakers he has written a letter to the state department and President Trump demanding more to be done to release Mohammed.
"If this were any other country, you would be seeing a much bigger effort. But for whatever reason, the Trump administration does not want to push the Netanyahu government to do what it needs to do," Van Hollen tells us.
"You have an American citizen who is being terribly mistreated, who has been beaten up, who has been deprived of adequate food and nutrition, and I haven't heard much from the US government. I haven't heard anything from the secretary of state. I mean, Donald Trump himself. I mean, who says that he is the 'America First' president?"
Mohammed is being held without charge at Ofer prison in the West Bank. It also houses adult detainees, including some who have been convicted of the most serious terrorist offences including murder.
Mohammed's case has become relatively high profile because he is an American citizen.
But there are around 350 Palestinian child security detainees being held in Israeli jails, according to the Israeli Prison Service.
Many have never been charged and human rights groups, as well as the United Nations, say some have suffered abuse and torture.
"We should be demanding justice," says Van Hollen.
As I leave Zahar Ibrahim's holiday home in al-Mazraa al-Sharqiya, he looks drained and alone. The house is sparse. Just a set of weights to fill his time.
All he can do is wait.