Four full-time police officers whose salaries will be paid with federal stimulus money started work in Modesto earlier this week. The city won a $4.4 million grant in July that will pay for 13 officers over the next three years. Modesto used part of the money to hire back eight officers who were laid off in July. The rest of the funds went toward filling five vacancies at the department. One vacancy was filled in September, the other four were filled this week. The Modesto Police Department was one of about 1,000 law enforcement agencies nationwide awarded $1 billion from the federal stimulus program. Agencies in Stanislaus, Merced and San Joaquin counties won $25.3 million for 75 officers.