There are three common relative markers: lo ke, ke, and i each meaning ‘who, which, that’. Patiño Rosselli (1983: 175–178) examine these pronouns in considerable detail, and also provide a rich set of examples. While a Spanish derivation of lo ke and ke seem certain, the origin of i remains a mystery.
Since ke is only used in subject function, it counts as a relative pronoun, while the others count as relative particles.
It is not known whether these particles differ in any way from each other in terms of their function or semantics. There is sufficient evidence, however, to affirm that (a) adjectival subordinate clauses can be introduced by lo ke, ke, as well as i, but that (b) pronominal relative clauses, on the other hand, can only be introduced by lo ke and i.