I found that in the Old Testament, the following19 acts were to be punished by death:-
Deliberate homicide (Gen 9:6, Exod 21:12-14, Lev 24:17). One witness was insufficient (Num 35:30).
Attacking or cursing a parent (Exod 21:15, 17, Lev 20:9), or refusing to obey a parent when being disciplined for being profligate and a drunkard (Deut 21:18-21).
Kidnap (Exod 21:16).
Being a sorceress or medium or spiritist (Exod 22:18, Lev 20:27).
Having sex with an animal (Exod 22:19, Lev 20:15-16).
Sacrificing to any god other than the Lord (Exod 22:20).
Working on the Sabbath day (Exod 31:14-15, 35:2).
Giving children to Molech by passing them through the fire (Lev 20:2).
Adulterer and adulteress (Lev 20:10-12).
Sleeping with your father's wife or daughter-in-law (Lev 20:11-12).
A man sleeping with a man (Lev 20:13).
A man marrying both a woman and her mother (Lev 20:14).
Cursing the Lord and blaspheming his name (Lev 24:16).
Non-Levites disassembling the tabernacle (Num 1:51).
Non-High Priests approaching the sanctuary (Num 3:38, 18:7).
A prophet instructing people to follow another God, and a town that accepts his message (Deut 13:1-18, 17:2-7); also a prophet who presumes to speak in God's name anything God has not commanded him to say (Deut 18:20).
A man showing contempt for a judge or a priest ministering to the Lord (Deut 17:12).
Female promiscuity before marriage (Deut 22:21).
Some thoughts arising
The New Testament explains how guilt can be dealt with. See Acts 13:38 -39! We have all sinned and fallen short of God's glory (Rom 3:23), but if we confess our sins, God forgives us and the blood of Jesus purifies us from all unrighteousness (1 John 1:7 & 9). God will give his Holy Spirit to evil people like us who ask him (Luke 11:13), and the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self control (Gal 5:22-23). Great news.
David Pennant, Woking, UK