Psalm 139:7–8 asks a question that is really a statement of faith: "Whither shall I go from thy spirit? or whither shall I flee from thy presence? If I ascend up into heaven, thou art there: if I make my bed in hell, behold, thou art there." The Hebrew word for "hell" — sheol — is the place of the dead, the furthest possible removal from ordinary life. David says God is there. This is not a doctrinal argument about what happens after suicide. It is a statement that there is no place — including the furthest — where God's presence does not reach.
Romans 8:38–39 exhausts every category of separation: death, life, angels, principalities, things present, things to come, height, depth — "nor any other creature, shall be able to separate us from the love of God." Paul's list is meant to be comprehensive. Whatever happened in the final moments of the person you lost, nothing in Paul's exhaustive list is sufficient to separate from God's love. The manner of death is not on the list.
Commentary is from a charismatic Protestant perspective, drawing on KJV text and public-domain sources including Spurgeon, Andrew Murray, and Matthew Henry.