Sweikat had been accepted into Western Michigan University (WMU), but Saudi authorities arrested him in 2013 at the airport before boarding the plane to start his university education to study finance.
Michigan officials and activists, who had been pushing to stop the execution, have condemned the killing, calling on the US government to hold Saudi Arabia accountable.
"We learned the news yesterday along with all others. It's certainly distressing and tragic news. It's hard to fathom," Paula M Davis, a spokeswoman for WMU, told Middle East Eye.
Sweikat was killed along with 36 others -- mostly activists from the country's Shia minority -- after being convicted on "terror" charges stemming from anti-government demonstrations.
According to the London-based human rights group Reprieve, Sweikat endured torture at the hands of his captors before his execution.
"He was severely beaten all over his body, including the soles of his feet, and convicted on the basis of a confession extracted through torture," Reprieve said in a statement.
The executions mark the latest round of increasing human rights abuses by Saudi Arabia under the leadership of powerful Crown Prince Mohammed bin Salman.
One of the 37 victims of the executions had his beheaded corpse put on public display on Tuesday, according to Human Rights Watch.
"Saudi authorities will inevitably characterize those executed as terrorists and dangerous criminals, but the reality is that Saudi courts are largely devoid of any due process and many of those executed were condemned based solely on confessions they credibly say were coerced," Michael Page, deputy Middle East director at HRW, said in a statement.
Still, despite the growing scrutiny of Saudi Arabia's rights violations, US President Donald Trump has rarely criticized Riyadh, even as outrage grows in the US over the murder of journalist Jamal Khashoggi and the detention and execution of dozens of activists.
'Surprised and stunned'
Ali Tinai, the head of WMU College Democrats, a student group on campus, said Trump has failed Sweikat and other victims of the Saudi government.
"By being silent and not taking action to prevent incidents like this from happening, this administration is showing that it does not care about human rights," Tinai told MEE.
Both Democrats and Republicans in Michigan expressed outrage over the execution.
Democratic Michigan Congresswoman Debbie Dingell also condemned the "disturbing" killing of Sweikat.
"Mutjaba had a bright future ahead of him and Michigan was prepared to welcome him as a student. Instead, he faced inhumane torture and pain ultimately leading to his execution," Dingell said in a statement, vowing to promote free speech around the world.
Dingell serves a district with a large Arab population on the east side of the state.
Fred Upton, the Republican congressman who represents the city of Kalamazoo where the university is located, revealed that he had addressed Sweikat's case with Saudi officials.
"I was most surprised and stunned to hear the news about Mujtaba’a al-Sweikat, a young man that could have had a promising future ahead of him," Upton told MEE in an emailed statement.
"Rep. Debbie Dingell and I met early on with Saudi officials to voice our humanitarian concerns with his arrest. He was only 17 when he was arrested, and to suffer such a barbaric act is tragic. Our prayers are with his family and friends."
Campaign against execution
Local lawmakers and rights advocates also decried the execution.
Abdullah Hammoud, a Michigan state representative, urged Congress to impose sanctions against the Saudi government, saying that the increased pressure on Riyadh that occurred after Khashoggi's murder must be maintained to hold Saudi rulers accountable.
Hammoud called the torture and killing of Sweikat "egregious."
"He was a student who had a whole future ahead of him, who was coming here to excel, to further a life for himself and for a future family that he could have started," Hammoud told MEE. "It's saddening to hear."
For his part, Jon Hoadley, a Kalamazoo-based Democratic State representative, also said he was "saddened and disgusted" by the news of the execution.
"We had previously advocated for justice for Mujtaba al-Sweikat," Hoadley wrote in a Facebook post.
"He was a young man seeking an education at Western Michigan University. However, since he protested his government, he was detained, isolated, subjected to a sham trial, and ultimately - if the reports are true - beheaded."
Hoadley and other officials led a campaign to lobby Trump to intervene and halt the execution after news of the death sentence against him emerged two years ago.
"I request that you contact Saudi Crown Prince Mohammed bin Salman as soon as possible and urge him to stop the executions and commute the death sentences," Hoadley wrote in a letter to Trump in July 2017.
"Any government that stands idly by while a young man loses his life in such a barbaric way, for no real crime, is complicit in his death."
The letter was co-signed by Michigan's entire Congressional delegation - 14 members of the House of Representatives and two senators.
Hearing and death sentence
In August 2015, Mujtaba was brought before the Specialized Criminal Court in Riyadh. Mujtaba was not given prior notice of the hearing and was not given access to a lawyer. He was convicted solely based on a “confession” extracted under torture, Reprieve said in a statement.
In June 2016, the Riyadh court sentenced Mujtaba and 13 other co-accused to death, rejecting the Bureau of Prosecution and Investigation’s submission for a mandatory death sentence, instead issuing its decision under the court’s discretionary powers.
Despite his raising his torture and ill treatment at trial, and the United Nations' frequent communications on his behalf, the kingdom did not provide him with an effective way to complain, did not conduct an investigation in line with the Istanbul Protocol, and did not commute his death sentence for running counter to the prohibition against execution for juveniles, Reprieve said.
The government eventually responded to the UN Special Procedures in January 2018, denying all allegations made in the complaints and stating that the evidence provided by the United Nations was false.
100 executions this year
The kingdom has executed more than 100 people in the first four months of 2019, and is on track to kill more than 300 this year, Reprieve posted on Twitter on Tuesday.
"This is another egregious display of brutality by Crown Prince Mohammed Bin Salman," Reprieve Director Maya Foa said in a statement. "At least three of the people executed today were arrested as teenagers and tortured into false confessions. Many were convicted of non-lethal crimes, such as attending protests.
"That the Saudi regime believes it has impunity to carry out such patently illegal executions, without notice, should shock its international partners into action. The US and the UK, in particular, must ensure there are consequences, and that no one else is unlawfully executed for exercising their right to freedom of expression.”
As news of al-Sweikat's imprisonment was publicized in 2017, faculty at Western Michigan issued an open letter calling for his release.