Andrew Mountbatten-Windsor, formerly known as Prince Andrew, was arrested Thursday morning by British police on suspicion of misconduct in public office.
He was released under investigation on Thursday evening, according to Thames Valley Police, and has not been charged.
The arrest comes after the emergence of documents released by the U.S. Justice Department which showed communications between Andrew and the late convicted sex offender Jeffrey Epstein.
Andrew has previously denied wrongdoing with respect to Epstein.
Watch Impact x Nightline, "The Prince, The Predator and The Arrest," now streaming on Disney Plus and Hulu.
Here is what to know about the alleged offense.
The Crown Prosecution Service, who prosecute criminal cases in England and Wales, defines misconduct in public office as a common law offence that involves "serious wilful abuse or neglect of the power or responsibilities of the public office held."
The agency states on its website that "there must be a direct link between the misconduct and an abuse of those powers or responsibilities."
"The Court of Appeal has made it clear that the offence should be strictly confined, and it can raise complex and sometimes sensitive issues," it states.
The Crown Prosecution Service further defines the offense as occurring when a public officer "wilfully neglects to perform their duty and/or wilfully misconducts themselves."
The act must "amount to an abuse of the public's trust in the office holder" and be committed "without reasonable excuse or justification," the agency states.
The definition of a public officer, as defined by the agency, is broad but can include "judges, magistrates, registrars, [and] coroners," as well as police, immigration officers, elected officials, civil servants and prison staff.
"There is no simple definition of a public officer, and each case must be assessed individually, taking into account the nature of the role, the duties carried out and the level of public trust involved," the agency states.
Andrew appeared to share with Epstein sensitive information stemming from his role as the U.K. trade envoy in 2010 and appeared to discuss potential business dealings with the disgraced financier while working for the government, emails released by the Justice Department suggest.
Emails sent by Andrew show the former prince passing along what he described as "confidential" information stemming from his government role to Epstein, and other emails -- including some sent by his former liaison -- suggest that Andrew discussed Epstein's connections in his personal dealings.
According to the Crown Prosecution Service, the offense "carries a maximum sentence of life imprisonment."
According to U.K. law, authorities can hold the former prince for up to 24 hours before they charge him with a crime or release him.
In special cases, authorities may apply for a longer hold of 36 to 96 hours if a suspect is suspected of a serious crime.
Andrew's elder brother King Charles III issued a statement in the wake of Andrew's arrest on Thursday, saying the royal family would cooperate fully with authorities.
"What now follows is the full, fair and proper process by which this issue is investigated in the appropriate manner and by the appropriate authorities. In this, as I have said before, they have our full and wholehearted support and co-operation," Charles said. "Let me state clearly: the law must take its course. As this process continues, it would not be right for me to comment further on this matter."
The king added that his family would continue to fulfill its duties and service to the British public in the interim.
Both Charles and his wife Queen Camilla were spotted attending events on Thursday, with the queen visiting Sinfonia Smith Square Hall in London to hear an orchestral performance and Charles attending Tolu Coker's London Fashion Week show.
Prince William, the heir to the British throne, and his wife Kate, the Princess of Wales, are not expected to issue a separate statement, but they support the king's statement, ABC News understands.
Andrew has not yet issued any statements regarding his arrest.
Watch Impact x Nightline, "The Prince, The Predator and The Arrest," now streaming on Disney Plus and Hulu.
