Being Catholic myself I tried to explain that he would need an annulment from his previous marriages for her to be able to marry him -]in the Church/-].
Correction: to marry him at all
Yes, he must be found free to enter into a marriage. That will require the examination of all prior marriage(s) either of them has attempted. There are many ways that a prior marriage could be invalid: nullity, lack of form (if one party was Catholic), dissolution of a natural bond, or Ligamen.
lcdiocese.org/Annulments/determine.htm
His first marriage was between himself and a Catholic but they were married by a JP, but his first marriage was never annulled. Does that make his second marriage invalid? If so will his second marriage need to be annulled also or will it even be recognized?
Each marriage is considered independently, beginning with the first.
If the facts are as presented-- he married a Catholic at a JP and the Catholic did not have a dispensation (and he can prove the first wife was Catholic through sacramental records) then it was indeed a “lack of form” on the part of the Catholic and no marriage took place.
That would in turn give presumption of validity to the second marriage attempt. That marriage attempt would also have to be investigated.
The baptismal status of both parties to a marriage attempt, any prior marriage(s) on their parts, and other factors are all relevant. Therefore, we can say no more here on this forum.
It is time for your friend to have a sit down appointment with the Catholic pastor in his area and start completing some preliminary investigation paperwork that will help the priest know what the relevant facts are and how to proceed with the case.