A motorist who drove through give-way markings, collided with a cyclist and then dragged him, trapped under his car, for more than a mile has been found guilty of murder.

Simon Richardson, 35, crashed into headteacher Michael Mullins, 56, who was cycling home from work at Stretford grammar school, Greater Manchester, on the evening of 20 April. Mullins hit the bonnet and windscreen of Richardson's Volvo XC90 and then went under the car, becoming entangled in the suspension.

Richardson continued to drive for more than a mile, knowing that the trapped cyclist was just inches under his feet, a trial at Manchester Minshull Street crown court heard.

Members of Mullins' family were in tears after the guilty verdict was delivered on Friday. The trial judge, Mrs Justice Brunner KC, discharged jurors from taking jury service again for 10 years and told them: "This was, I know, an upsetting case and there was evidence which you may have found distressing."

Richardson had denied knowing the father-of-two was under his car but the prosecutor Phil Barnes KC said the defendant knew "and he inevitably knew what the consequences of driving on would be, and he did it anyway".

"For a split second after the collision, for a brief moment, he possibly thought about doing the right thing and getting out and taking ownership of what he had just done and help the man he had just run down.

"But Simon Richardson did not get out. He did not do the right thing. He chose to drive away. The obvious reason is because he wanted to escape the consequences of what he had just done."

Richardson's front-seat passenger, his cousin Gabrielle Debotte, told the trial they both heard "moaning" from outside as he drove away from the collision scene. Giving evidence for the prosecution, she said Richardson went on to say: "He's under the car."

The collision happened in the village of Warburton. The court heard Richardson drove to a secluded farm track in Lymm, 1.3 miles away, in an attempt to dislodge Mullins.

After he stopped, Richardson twice tried to pull Mullins out, before returning to the car and driving sharply and deliberately from side to side before mounting a grass verge, the court heard. Mullins was finally released but was then driven over again as Richardson reversed and drove away.

A motorcyclist followed a trail of blood from the collision spot and discovered Mullins alone and barely breathing on the grass verge, the court heard. Emergency services attended but were unable to save Mullins, from Northwich, Cheshire, who died from multiple injuries.

Richardson was arrested the next day after a police vehicle pursuit. He denied murder as he claimed he did not realise Mullins was underneath his car and said he did not get out of his vehicle to try to free him.

In a statement, the family of Mullins said: "He was devoted to his family and our lives will never be the same. A gap has been left in our hearts and within his role as a headteacher of Stretford grammar school."

In his closing speech to jurors on Tuesday, Jaime Hamilton KC, defending, said: "You are likely to hold Simon Richardson in contempt. That contempt may well manifest itself in a loathing of Simon Richardson and, in fairness, you are probably right to. Because it is right that we acknowledge it was the actions of Simon Richardson that led to the death of Michael Mullins.

"Not only is he responsible for the death of Michael Mullins, he acted in the most selfish of ways with one thought in his mind – himself. But that does not make him guilty of the homicide offences on this indictment."

Jurors went out to consider their verdict on Wednesday and returned to find Richardson guilty on Friday. The judge said she would sentence him on Monday.