A promising George Washington University medical student told police he killed his best friend after catching him having an affair with his girlfriend.

24-year-old Rahul Gupta was charged with second-degree murder in relation to the stabbing death of his best friend and Georgetown law student Mark Waugh early Sunday morning in Silver Springs, Virginia.

According to police, Gupta, his 23-year-old girlfriend, Waugh and one other had spent Saturday out celebrating Gupta’s birthday.

Best friends: Rahul Gupta (right) told police that he killed his best friend, Mark Waugh (left), after catching him having an affair with his girlfriend

Dark turn: Gupta, his girlfriend, Waugh and another spent Saturday night out celebrating Gupta’s birthday. The first three later returned to the girlfriend’s apartment where they continued to drink shots. Waugh was found dead at 3:30am Sunday morning

After drinking, Gupta and Waugh returned to Gupta’s girlfriend’s apartment in Silver Springs where the three continued drinking shots of alcohol.

Neighbors later reported hearing loud noises coming from the apartment, like people were moving furniture.

Shortly before 3:30am Sunday morning, police responded to a 911 call made by the girlfriend.

When they arrived on the scene, police reported hearing movements and yelling inside but no one answered the door when they knocked.

Trouble in paradise: Gupta told police that he caught Waugh and his girlfriend cheating and that’s why he killed him. Above, two pictures of Gupta with a girlfriend uploaded to his Facebook within the last year

Police opened the locked door and the girlfriend approached the officers with blood on her and said: ‘I don’t know what happened. Can you tell me?’

Officers noted seeing blood on the walls of the kitchen and living area and Gupta lying on the floor, covered in blood.

They asked Gupta if he was hurt but he said: ‘I don’t think so’.

When they asked him what had happened, he replied: ‘I walked in on my girlfriend cheating on me. My girl and my buddy were cheating. My girl was cheating with my buddy. I walked in on them cheating and I killed my buddy.’

Officers found Waugh lying on the floor unresponsive and he was pronounced dead. He was covered in blood with ‘multiple cutting and defense-type injuries to his body’. Police say a knife was used in the attack.

Who to believe? While Gupta says he was woken up by his girlfriend yelling, the girlfriend told police she was woken up by Gupta’s yelling. She says she found him kneeling next to a bleeding Waugh and he told her to call police. Above, a picture of Waugh

Gupta and his girlfriend have a differing account of what happened before police were called.

Gupta told police officers that he was woken up by his girlfriend yelling.

It’s uncertain whether he actually saw something going on, but he told officers that he thought Waugh and his girlfriend were in a relationship behind his back and that Waugh had tried to harm him and his family.

At police headquarters, Gupta admitted that he made a mistake, but added: ‘He tried to kill me, though’.

Defense? While being questioned by police, Gupta admitted that he made a mistake but also said that Waugh tried to kill him

But the girlfriend says Gupta woke her up and not the other way around.

She says she doesn’t remember anything after having the last shots back at the apartment but that she was later woken up by Gupta yelling and telling her to call 911.

That’s when she woke up and saw him kneeling next to Waugh who was bleeding heavily.

As of Monday, Gupta was being held at the Montgomery County Jail on $2million bond.

The Gazette spoke to Nancy Waugh, the victim’s mother, yesterday who said she was still in shock and couldn’t believe what had happened.

She said her son and Gupta had been best friends ever since they met attending Langley High School in McLean, Virignia.

Close: Both Waugh’s mother and Gupta’s father expressed shock after hearing about the killing. Waugh’s mother Nancy says the two were best friends ever since they met attending Langley High School

‘It’s very hard right now,’ Mrs Waugh said.

Full of promise: After graduating Magna Cum Laude from James Madison University, Waugh spent a year teaching debate in South Korea. He had just started his first year at law school at Georgetown

WJLA was able to speak with Gupta’s father over the phone who said he was ‘saddened’ and ‘very surprised’ by Waugh’s death and his son’s subsequent arrest.

Waugh had graduated Magna Cum Laude from James Madison University in May 2012, and went on to spend the following year in Daegu, South Korea teaching debate.

This fall, Waugh had started his first year of law school at Georgetown, and was inducted into the Phi Beta Kappa honors society.

Gupta had a similarly bright future. He earned his undergraduate degree from George Washington University and was back at the school studying to become a doctor. He also earned a master’s degree in physiology from Georgetown.

Fellow Langley High School-alumnus David Barton spoke about both men in The Breeze – James Madison University’s student newspaper.

He remembers both men for being extremely intelligent in their respective fields, Waugh in liberal arts and Gupta with science and math.

‘It’s very shocking when something like this happens when you know each person involved,’ Barton told The Breeze. ‘You think that – how can people you think to be rational have something like this take place. You just hope that the situation could have de-escalated’.

Smart: Gupta was similarly accomplished. He got his undergraduate degree from George Washington University where he was last studying to become a doctor. He also got a master’s degree in physiology from Georgetown

Read more: Daily Mail