|Shash tshinipati tekushinian.
|You were already asleep when I arrived.
The Independent Indicative Past conjugation (#03), like the form tshinipati above, is used for things that happened in the past.
|Shash nipapan ka takushinian.
|S/he was already sleep, when I arrived.
It can be used with the modal preverb tshipa.
|Shashish an tshipa tshitutepan uipat aieshkupitakue.
|S/he would have left if I had arrived.
It can be used with the volitional preverb ui.
|Shash tshui nipati …tekushinian.
|You already wanted to sleep / You were about to sleep …when I arrived.
|Shash ui nipapan …tekushinian.
|He already wanted to sleep / He was about to sleep …when I arrived.
|Shash an tshipa ui tshitutepanat utakushit.
|They should have already left yesterday.
More on preverbs…
Link to the conjugation guide.