Wergenbauer, who was one of the people who decided to hire Mortimer, described him as being very "polite" and having "great references."
Anil Shah, the president of the company, said that Mortimer was hired about a month ago but took his first two weeks off to arrange child care for his children.
"He made it clear that he was very involved in their growth and had been out of work until now spending time with [his kids]," said Shah.
Shah said that up until the last minute on Monday night, the last day Mortimer was at work, he was making calls to clients and was making "good progress."
Asked if Mortimer ever showed signs of having a bad temper, Shah laughed.
"Temper? Far from it," said Shah. "He was very calm and very cool. That's why we're worried about him."
Neighbors who knew the family are stunned by the grim discovery.
"It's shocking," neighbor Sam Bejikian told ABC News' Boston affiliate WCVB-TV. "I don't know what to say. I just saw them yesterday, you know, like, playing outside. Very happy family. Very shocking."