Hello again and thank you for that additional information. There may be an additional course of action under the statute below, which is the RI "enticement" statute. So, that would be two charges that are possible in RI. In Mass, if she was living there and they did not have sex there until she was 16, then there probably is no statute other than the one I shared before, although there is an "enticement" statute in Mass., it applies to children under 16.
Finally, if he had convinced your sister to go to RI, rather than her going anyway because she was going to a wedding, there might be a Federal criminal
action since he would have been getting her to cross state lines to engage in criminal conduct.
So, if she is up to it, she should consider filing a complaint with RI and the Mass law enforcement authorities and see where their investigation
As far as proof goes, as I touched on before, they will start with her statement and then try to establish other facts/evidence which support her statement of the facts. That would be done by interviewing all of the potential witnesses and attempting to interview the accused, as well as looking at any physical evidence, like diaries, letters, emails, photos, etc., to establish their case. These cases do sometimes come down to one person's word against the other. But most prosecutors will not take a case to trial
these days unless they have more than a he said, she said. That is the unfortunate fact. They just don't want to spend time, money and their reputation on a case they "know" they can't win. But, as I mentioned, they will investigate and try to put facts together to build a case if they are there.
§ 11-26-1.5 Enticement of children
(a) A person shall be guilty of a felony if that person attempts to persuade, or persuades a minor child under the age of sixteen (16) years, whether by words or actions or both, with intent to engage in felonious conduct against that child to either:
(1) Leave the child's home or school;
(2) Enter a vehicle or building; or
(3) Enter an area, with the intent that the child shall be concealed from public view; while the person is acting without the authority of: (i) the custodial parent of the child, (ii) the state of Rhode Island or a political subdivision of the state, or (iii) one having legal custody of the minor child. Nothing contained in this section shall be construed to prevent the lawful detention of a minor child or the rendering of aid or assistance to a minor child.
(b) Every person convicted of a violation of the provisions of this section shall be guilty of a felony, and shall be punished by imprisonment for not more than five (5) years, or by a fine of not more than five thousand dollars ($5,000), or by both fine and imprisonment.
(c) Every person convicted of, or placed on probation for a violation of this section, may be ordered to attend appropriate professional counseling to address his or her behavior