In In re Melinda J. (1991) 234 Cal. App. 3d 1413, the "single mother who supported her heroin addiction by engaging in prostitution and illegal drug sales . . . . left the minor with a casual acquaintance and never returned." ( Id. at p. 1415.) Filing a dependency petition, SSA "sent a certified letter to mother's last known address, contacted the post office to determine a forwarding address, and mailed a letter to the grandparents asking for help in locating mother." ( Id. at p. 1416.) It undertook a comprehensive search, uncovering "several more addresses, to which it sent additional certified letters with copies of the petition." (Ibid.) When the mother failed to appear at the jurisdictional-dispositional hearing, her default was entered. A few days later, she was jailed, and for four months, the social worker visited her, counseled her and provided her with referrals to be utilized upon her release. The efforts were to no avail. Released before the six-month review hearing, the mother disappeared again. SSA repeated its efforts to notify her of the hearing; she did not appear. SSA conducted another absent parent search and sent certified letters regarding the 12-month review hearing to all addresses. The mother failed to respond or appear. She finally signed an acknowledgment of receipt of notice of the permanency hearing at which her parental rights were terminated. ( Id. at pp. 1416-1417.) The Melinda J. court rejected the mother's due process notice challenge. It stated, "SSA made sincere and extensive efforts to locate the mother; even with the benefit of hindsight, we see nothing else that should have been done. 'It has been recognized that, in the case of persons missing or unknown, employment of an indirect and even a probably futile means of notification is all that the situation permits and creates no constitutional bar to a final decree foreclosing their rights.'" ( In re Melinda J., supra, 234 Cal. App. 3d at p. 1419.) In response to the mother's contention the judgment should be reversed because two hearing notices were mailed with a shorter lead time than required under the statute, i.e., respectively nine days and seven days prior to the hearings, rather than within the prescribed 15to 30-day advance period ( 366.21, subd. (b)), the court found "reversal based solely on the SSA's noncompliance with the time periods would place ' "undue weight on a matter of procedure rather than substance.' "" (234 Cal. App. 3d at p. 1419.) It added that, in any event, the mother did "not suggest that timely mailing to her last known address would have secured her presence at the hearings." (Ibid.) Thus, the agency's "lack of strict compliance with the statutory time frames for notice, in the absence of prejudice, did not render the subsequent proceedings void." (Ibid.)