This undated image shows Mark Mangaccat and his wife and child. Police say the 31-year-old was fatally shot in Daly City, Calif. on Wednesday, April 25, 2018. KGO-TV

DALY CITY, Calif. -- A man who picked up his fiance from her last shift at San Francisco International Airport last week and planned to move with her to Las Vegas was fatally shot by a fellow SFO worker who sought a romantic relationship with her, San Mateo County District Attorney Steve Wagstaffe said.Kevin Prasad, 31, of South San Francisco, and Donovan Rivera, 25, of Hayward, are charged in the murder of 31-year-old Mark Mangaccat last Wednesday.That day, Mangaccat drove to pick up his fiancee, the mother of their 3-year-old child. Prasad, who worked at SFO with her, had been trying to develop a romantic relationship with her and urged her to dump Mangaccat but she had rebuffed his advances, prosecutors said.Rivera allegedly drove Prasad as they followed Mangaccat, who picked up his fiancee and returned to their home on Abbot Avenue in Daly City.As Mangaccat was backing the vehicle into the garage, Prasad allegedly walked up and fired five to six shots into the car, killing him while not hitting the fiancee, prosecutors said."The working proposition for the motive is, 'If I kill him and get him out of the way, then I could be there to start the relationship with the grieving widow,'" Wagstaffe said. "That's pretty bizarre."Wagstaffe said the couple was planning on moving to Las Vegas after living with Mangaccat's family in Daly City and said last Wednesday had been the fiancee's last shift."I saw my son, with the blood in his mouth, and I saw a hole, and I said, what happened? So I ran upstairs and called 9-1-1, and came back, and tried doing this (CPR) to my son," said Mangaccat's mother, who was inside the home at the time of the shooting.Following the shooting, Prasad allegedly ran back to the car and Rivera drove them away from the scene, but investigators were able to identify and arrest them a day later, according to Wagstaffe.The two defendants made their initial court appearance Monday on murder charges with a special circumstance of lying in wait.They did not enter pleas and will return to court on May 8 for the appearance of their appointed Private Defender Program attorneys and to possibly enter pleas.Daly City police have not released any information about the case and referred any inquiries about it to the district attorney's office.Social media posts about Mangaccat mourned his death."He was one of the nicest people," one post read. "I still can't believe it."Meanwhile, three weeks ago Prasad apparently testified at a San Francisco Board of Supervisors hearing on raising minimum wages for workers, saying he was a security officer at SFO who is also "a veteran and part of the working poor."Mangaccat's fiance was beside herself saying, "He's my life. He's everything."The clip of Prasad speaking at the hearing was posted on the Facebook page for Airport Workers United, a union of airport workers.