A man who was cycling from Maryland to Miami to propose to his girlfriend has been stabbed to death by a homeless man after stopping for a snack at a McDonald's.

Police officers found an engagement ring in Kevin Adorno's pocket when they rushed to the fast-food restaurant in Vero Beach, Florida, on Monday evening.

Adorno had been on the phone to his girlfriend when he was attacked without warning by Rene Herrera Cruz, who told police that he thought Adorno was plotting to kill him, authorities said.

Adorno's girlfriend told police that she heard his phone drop before a wail of sirens, FoxCT reported.

Tragedy: Kevin Adorno (left) was killed by a homeless man after he stopped at a McDonald's to get a snack as he biked down the east coast. Once in Miami, he was going to propose to his girlfriend Elyse (right)

Adorno, from Farmington in Connecticut, had left home in mid-August to complete his dream of cycling down the east coast. Last year, he and his sister had cycled from Maine to Maryland, and this year, he planned to finish the rest of the journey.

He had shared dozens of photographs along his route, including images of his bike propped up on sandy beaches and in city centers.

His girlfriend, Elyse, had planned to fly down and meet him 20 miles from his destination so that she could finish the journey with him. When they reached Miami, he had planned to propose to her.

But on Monday evening, he stopped at the restaurant to charge his phone and get a snack, WPBF reported. A witness said he went outside to use his phone when he was attacked around 9.30pm.

'Killer': Rene Herrera Cruz, 59, told police he saw Adorno looking at him before making a phone call and thought he was instructing people to kill him. He admitted to stabbing Adorno in the chest and arm, police said

Scene: Adorno had stopped at this McDonald's in Vero Beach, Florida for a snack and to charge his phone

Police said he was repeatedly stabbed in the arm and chest and, as he began losing a lot of blood, he collapsed near a bathroom.

'Although EMS and Fire Rescue also assisted in the attempts to save Adorno, he succumbed to his wounds and was pronounced deceased a short time later at the IRMH,' police said.

The 59-year-old suspect, who was arrested nearby on Monday night, told authorities that he had attacked Adorno because he believed he was on the phone instructing people to kill him.

He said he also thought Adorno was taking photos of him and that he felt threatened.

Authorities found a bloodied 12-inch blade that Cruz had allegedly thrown into a bush after the attack. He had also taken off his dirty shirt and discarded it.

Cruz, who was known to local police, has been charged with first-degree murder.

Together: Elyse had planned to fly from Connecticut to join her boyfriend for the last 20 miles, and once they reached Florida, he was going to propose to her, family said. Police found an engagement ring in his pocket

Plans: On Facebook, he shared this map of his planned route down the east coast. Last year, he and his sister cycled from Maine to Maryland, and this summer he had hoped to finish off the journey

Excitement: Throughout his journey, he shared photographs to Facebook, showing his various stops

Journey: He shared this image of the Florida border on August 30, two days before he was killed

Vero Beach Police Chief David Currey told NBC that they had dealt with Cruz just the night before.

'He called us from Burger King right across the street and he told responding officers that individuals were looking for him or were after him,' Currey said.

Adorno, who owned a graphic design business based in Hartford, Connecticut, was an outgoing, adventurous friend and brother, family said.

'Just a pure soul as charismatic as anyone could ever be, smile from ear to ear always generous,' close friend Kenneth Silva told WPFB. 'Just a really good guy.'

Family members wrote on Facebook that they were 'absolutely devastated' by the loss.

Adorno's family is now traveling to Florida to retrieve his body and help with the investigation.