perhaps I can help. I am a former mormon and a catholic now. I was in a bishopric in the mormon church and participated in church courts that upon a few occasions excommunicated people.
in the mormon church venial sins are confessed to God only. mortal sins are confessed to the bishop. (like a pastor) this is not a regularly scheduled rite like catholic reconciliation but is by appointment. (however LDS are real into interviewing their members regularly which often results in confession) if a sin is serious enough and the person appears to be sincerely repentant then the bishop will usually schedule a “church court”. this is a tribunal made up of the bishop and his two counselors. the ward clerk is present to record the proceeding. the indivdual confesses to the group and they ask questions to fully understand what happened and why and what the individual is doing to repent and sin no more. Once this is complete the person is sent out and the bishopric deliberates on what should occur. in the end the bishop decides but he always listens to the counselors first. once the decision is made the person is brought back in and told their fate.
They can be told one of many things: 1) your repentance is sufficient and everything goes back to normal.(rare but allowed) 2) they are put on “probation”. this restricts them from praying publicly on behalf of a group (like a sunday school class), taking communion and serving in any ministerial callings. If male they are barred from exercising any priesthood authority. they must meet on a regular basis with the bishop until he decides to end their probation. 3) they are disfellowshipped. this is a more severe form of probation that is indefinite as well (at least a year) and requires that a new court be reconvened to allow them back into full fellowship. 4)excommunication. their membership is revoked and all sacraments invalidated. they are a nonmember and require special permission to “rejoin” the church.
coming back from excommunication one must be rebaptized. if they had been to the temple they must get a special ordinance called restoration of blessings to put their temple covenants back into effect.
sometimes if a person is blatantly apostate or considered a threat to other members or the good name of the church they will be exed without them going to their bishop.
in all cases of church courts they get an official summons notifying them of the time and place of their church court and why it is being called.
If a man holds the higher priesthood he cannot be exed by a bishop (except for some unique circumstances) but will have his court handled by the stake (like a diocese) high council with the stake president making the final decision.
These can be very painful experiences, especially for teenagers. adults to can feel the stigma of folks “knowing” by the fact they no longer callings or take communion.
things that require church courts include apostasy, adultery or fornication, felony crimes, serious misdemeanors, etc. murder is special in that the shedding of innocent blood is usually considered unforgivable. (except abortion which can not only be forgiven but sometimes is outright allowed)
getting back into full membership requires paying a full tithe, having a firm testimony in the LDS church particularly the restoration and the status of the 12 apostles and first presidency as prophets, seers and revelators and the BoM. one must remain chaste and free of of other serious sin and attend all church meetings. reading scripture and praying daily is required as well.