James “Whitey’’ Bulger’s girlfriend, Catherine Greig, is considering pleading guilty to charges of helping the gangster evade capture for more than 16 years, according to several relatives of Bulger’s alleged victims. Steven Davis, whose sister Debra was one of 19 people allegedly slain by Bulger, said a victims’ advocate for the US attorney’s office told him Friday that Greig’s lawyers have indicated that she wants to plead guilty to the single charge of conspiracy to harbor a fugitive. “There is no plea bargain,’’ said Davis, adding that he has been told that Greig has not been given a deal by prosecutors and faces up to five years in prison on the charge. Related 11/20/11: The long, unlikely journey of Cathy Greig It is unclear whether Greig could be forced to testify against Bulger, 82, a longtime FBI informant who is scheduled to stand trial in November in a sweeping federal racketeering case. That case alleges the South Boston crime boss killed 19 people in the 1970s and 1980s. A spokeswoman for the US attorney’s office declined to comment on the potential plea, and Greig’s lawyer, Kevin J. Reddington of Brockton, could not be reached. Greig, 60, is scheduled to stand trial May 7 and is expected to appear Wednesday in US District Court in Boston for a hearing on her case. ‘I have no animosity toward her.’ Bill St. Croix, whose sister was allegedly strangled by Bulger and St. Croix’s father “If that’s what she wants to do is plead guilty, what else can you do but accept that?’’ said Davis, adding that he would not be disappointed if there is no trial in Greig’s case because she is not charged with any of the slayings and has no prior record. “Get rid of her [case], and we can all focus on him, Whitey.’’ Patricia Donahue, whose husband Michael was allegedly shot and killed by Bulger in 1982 on the South Boston waterfront, said Friday that she was disappointed by the prospect that Greig would resolve her case without being compelled to testify against Bulger. “I’m not happy,’’ Donahue said. Greig’s sister, Margaret McCusker, answered the door at her South Boston apartment Friday night, but would not speak with a reporter. Prosecutors have asked relatives of Bulger’s alleged victims to meet with them Monday to talk about the proposed plea and any objections they may have, said Davis, whose 26-year-old sister was allegedly strangled by Bulger in 1981. Bulger, who fled just before his January 1995 federal racketeering indictment after being warned by his former FBI handler that he was about to be arrested, was a fixture on the FBI’s 10 Most Wanted list. He was finally captured on June 22 in Santa Monica, Calif., with Greig, a former dental hygienist who lived in South Boston and Quincy. The FBI found more than $800,000 cash and 30 weapons hidden inside the walls of the rent-controlled apartment where the couple had lived as Charles and Carol Gasko for at least 13 years, according to the FBI. They also found numerous false identities allegedly used by the couple. In court last November, prosecutors said they planned to bring additional charges against Greig within a few weeks, possibly involving the weapons and fake identities. But no new charges been brought against her. “I would like to see her charged with the guns and the money they found in California,’’ Patricia Donahue said. “I don’t really care about her [Greig], but I’m not happy with the way the government is handling this.’’ Donahue’s son, Shawn, said his family was hoping prosecutors could explain to them the status of the potential charges against Greig stemming from the discovery of the guns and cash in the apartment. Prosecutors allege that Greig joined Bulger on the run in early 1995 and helped him evade capture by running errands for him, picking up his prescriptions, and paying their utility bills. “If she’s just pleading out to the harboring charge, she’ll be getting off easy,’’ Shawn Donahue said. He said his family also wants to know if Greig can be compelled to testify against Bulger. Since they were returned to Boston last year, Greig has remained jailed without bail at a Rhode Island facility, and Bulger is being held at the Plymouth County Correctional Facility. Bill St. Croix, whose 26-year-old sister allegedly was strangled in 1985 by Bulger and St. Croix’s father, Stephen “The Rifleman’’ Flemmi, said Greig has the right to plead guilty and he does not hold her responsible for his sister’s death. “I have no animosity toward her,’’ said St. Croix. “Her going to jail is not going to benefit anybody. I get no just deserts seeing this woman suffer.’’ Greig’s attorney, Reddington, has argued in court that her only crime was falling in love with Bulger and that she had no knowledge of any of his crimes. He also said she would not cooperate against Bulger. St. Croix said he believed Greig would cooperate against Bulger only if he advised her to do so to win some leniency. “I imagine she’s old school . . . and is going to keep her mouth shut and take one for the team,’’ St. Croix said. “I don’t think she would cooperate against Jimmy unless Jimmy and her had discussed this prior.’’