Four Washington-area persons and a Chicago man have been arrested in what D.C. police described as a scheme to illegally obtain the heroin substitute Dilaudid through fictitious prescriptions.

Police said the pills were sold on the street for $40 each, and that sales totaled about $5,000 a day during the last six weeks.

The pills were obtained, according to police, after a person falsely identifying himself as a Chicago physician called doctors in the area and said that one of his "patients" was visiting here and needed a prescription.

Police said the caller used enough medical terminology to convince the physicians of the legitimacy of the request. Messengers then picked up the prescriptions and had them filled, investigators said.

Three of the suspects were arrested Sunday night by Montgomery County police. They were charged with obtaining a controlled substance by fraud and were identified by police as Collette Susan Blais, 19, of Dale City; Bernard Igbedion, 27, of 6402 Seventh St. NW, and Helena Garey, 20, of 62 Q St. NW.

Two other suspects, Jon J. Edmisten Sr., 28, of Chicago, and Linda Rae Pryor, 25, of Woodbridge, were arrested later Sunday and were charged with attempting to obtain a controlled substance by fraud, authorities said.