The mother of Karina Vetrano, the young woman strangled as she went for a run in a Queens park two years ago, sobbed and clutched a cross as the prosecutor described in detail how her daughter was killed.

Vetrano's killing was vicious, the prosecutor said in his opening statements Monday at the trial of Chanel Lewis. She was grabbed as she ran along a secluded, marshy section of Spring Creek Park in Howard Beach on Aug. 2, 2016. Her killer punched her in the face, threw her to the ground and violently sexually assaulted her before strangling her, authorities have said. 

Vetrano died in that marsh, about a block from her own home. She was just 30 years old. Authorities have said she fought ferociously for her life. Her father was part of the search party that discovered her body, face down, 15 feet off the trail. It would be nearly six months before DNA evidence found underneath her fingernails led to an arrest. 

The man arrested was Lewis. He has pleaded not guilty to murder in Vetrano's death. His attorneys have said a taped confession -- during which Lewis admits killing and beating her but denies a sexual assault --  was wrongly obtained and should not be admissible in the upcoming trial. 

Lewis faces life in prison if he is found guilty. His family was in court Monday for the opening statements. Lewis, wearing a suit, looked at them briefly.