Police say they are concerned because the disappearance is apparently not consistent with her normal behavior.
Melissa, 34, and her husband Clinton have lived in Round Lake Park for six years. They are high school sweethearts, originally from Wisconsin, who have been together 20 years and married for 15 years. Melissa's husband says it is unlike his wife to leave the family and children behind. He is seeking counseling for the children because they are devastated.
"It's completely unlike her to just disappear like this," said Melissa's husband Clinton Jean Best. "She is just devoted to her kids. It's hard, very hard."
The stay-at-home mom was reported missing after failing to return home on Friday, April 15, after she dropped off her daughter, 15, at a friend's home in the Rosewood Apartments in Round Lake Park at about 1 p.m. Her daughter was the last person to see Best before she disappeared.
Less than a mile from that apartment complex, there is a pizza restaurant with surveillance cameras that Best passed on her way to and from the apartments. Police say those cameras captured Best's van coming and going.
Best reportedly usually makes dinner for her family every evening and on the day she went missing, she had set the food out on the counter. Police say she never made it home to cook the meal.
Later that afternoon, her husband came home from work. He says he thought his wife was shopping, but then it got later and later.
"I waited up and waited up for a while and I had to go to work the next morning, so I ended up falling asleep," said Clinton Best. "I got up the next morning and saw she still wasn't there."
"He still wasn't overly concerned because apparently, in the past, she has gone to a friend's house or a relative and stayed overnight - but normally, she's called," said Round Lake Park Police Department Chief George Filenko.
Police say Melissa Best was reported missing on Saturday. Clinton Best said that when he returned home from work on Saturday and realized that his wife still was not home, he immediately notified police.
"The husband works long hours," said Filenko. "So there is some time lapse between him getting home from work, sleeping, that type of thing, and again, not really knowing exactly where she may have gone. She does have a tendency sometimes to visit friends or relatives."
"She dropped off her daughter at a friend's house at a bordering community in Round Lake, and the presumption at that point was that she was driving back home," said Filenko. "This is not consistent with any type of past behavior."
Police say the investigation has hit a dead end.
"We absolutely have no information as to where she could be right now," said Filenko.
The police chief says officers have been to the Bests' home two times during the last couple of years for verbal disputes, but he emphasized that he believes that has nothing to do with Best's disappearance this week.
Police say the family's only cell phone ran out of minutes, so the mother doesn't have a cell phone, and the family does not have any credit cards.
Chief Filenko said her car -- a green 1993 Pontiac Transport minivan with gray trim and license plate A770405 -- is also missing.
Best is 5'4" with brown/blond hair and hazel eyes. She is married with two teenagers. She attends College of Lake County in Grayslake, Ill.
Anyone with information should call the Round Lake Police Department at (847) 546-7275.