Can concealment of purpose amount to murder by means of lying in wait?

The seminal case on whether concealment of purpose can amount to murder "by means of lying in wait" is People v. Tuthill (1947) 31 Cal.2d 92, 187 P.2d 16. Tuthill was discovered by his estranged wife sleeping on a bed in her cabin with a rifle concealed beneath him. When she woke him up and asked him why he was there, he pointed the rifle at her. She told him he was not going to shoot her and left; however, when she returned almost immediately, he shot and killed her. The defendant argued that there was no evidence of lying in wait, first, because there was no element of surprise or concealment and, second, because whatever lying in wait may have existed ended when his wife left. The court noted that there appeared to be no California case precisely defining the phrase "lying in wait," but that it had been applied in other jurisdictions to a number of factual situations wherein the victim had been aware of the physical presence of the aggressor but not his true purpose.