Former NFL tight end Kellen Winslow Jr. allegedly sexually assaulted two women and targeted other older women in a series of crimes in a Southern California community, offenses which a prosecutor described as being conducted in a "serial nature."

Attorneys for Winslow, 34, who previously played for the Cleveland Browns and other teams and who was arrested on Thursday, entered a plea of not guilty at a court appearance in San Diego County on Friday. He is being held without bail.

Winslow is charged with kidnapping, forcible rape, and other counts and if convicted faces multiple life sentences, Deputy District Attorney Dan Owens said. Winslow allegedly raped the two women after luring them into his car in separate incidents.

"These charges themselves are extremely serious, and it is clear to the people that these were committed against the most vulnerable victims in society," Owen said after the court appearance.

"The fact that they had the courage to come forward and report these criminal offenses, we took them very seriously, and the moment that we were able to proceed with the filing of charges we did so," he said.

Winslow allegedly committed the sex crimes against two women that he lured into his Hummer H2 in Encinitas on March 17 and May 13, Owens said in court. Prosecutors allege that he raped the women, ages 54 and 59, and threatened to kill them if they reported what happened.

Former NFL football player Kellen Winslow Jr., second from right, stands behind lawyers Brian Watkins, third from right, and Harvey Steinberg, right, during his arraignment, in Vista, Calif on June 15, 2018. Hayne Palmour / San Diego Union-Tribune via AP

Winslow also is accused of approaching a 55-year-old woman who was gardening outside her home in May and allegedly followed her and exposed himself, before she ran inside the home and called 911.

The former NFL player also stands accused of entering the mobile home of a 71-year-old woman on June 1 but left after he was confronted. Days later he repeated the move, allegedly entering another mobile home of an 86-year-old woman on June 7 but was caught by a neighbor and arrested for burglary a short time later, Owens said. No one was hurt in those burglary cases, but Owens told reporters that the intent was not theft but the commission of a sex offense.

Winslow's attorney, Harvey A. Steinberg, did not return a request for comment on Friday.

At the time of the June 7 burglary arrest, Winslow's publicist said an "overreactive neighbor" called police in that incident.

The publicist, Denise White of EAG Sports Management, on Friday released a statement from Winslow’s family that said they support him and that "we know the true facts will come out."

In this 2006 file photo, Cleveland Browns tight end Kellen Winslow Jr., left, hugs teammate Braylon Edwards after the Browns' 24-20 loss to the Pittsburgh Steelers in an NFL football game on Nov. 19, 2006, in Cleveland. AP

In arguing that Winslow be held without bail, Owens said that the San Diego Sheriff’s Department had Winslow under "continuous surveillance" after he posted bond following the June 7 burglary arrest, and that the sheriff’s department learned he was trying to sell the Hummer H2 vehicle — which is where authorities say two of the women were raped.

"It appears as though he was attempting to be able to destroy potential evidence,” Owens said.

Winslow spent 10 seasons in the NFL from 2004-13 with Cleveland, Tampa Bay, New England and the New York Jets. The former University of Miami star is also the son of NFL Hall of Famer Kellen Winslow Sr.

Once NFL's highest-paid tight end, Winslow was suspended in 2013 by the Jets for violating the league's performance-enhancing drug policy. In November of that same year, he was arrested after a woman told police she saw him masturbating in a parked car outside of a New Jersey department store, the Associated Press reported. Winslow was arrested for possession of synthetic marijuana, and the charge was dropped after he completed court-ordered terms.