What constitutes improper comments made by a federal prosecutor to a jury in a civil case?

A prosecutor's "improper comments" violate the federal Constitution if they " ' "so infect[] the trial with unfairness as to make the resulting conviction a denial of due process." ' " (People v. Cunningham (2001) 25 Cal.4th 926, 1000.) If a prosecutor's conduct does not violate the federal Constitution, it violates " ' "state law only if it involves ' "the use of deceptive or reprehensible methods to attempt to persuade either the court or the jury." ' " ' " (Ibid.) In a claim involving comments made before the jury, " 'the question is whether there is a reasonable likelihood that the jury construed or applied any of the complained-of remarks in an objectionable fashion.' " (Id. at p. 1001.)