From his two convictions by a jury in the Superior Court of trafficking in cocaine, the defendant appeals. He assigns as errors the denial of his motion to suppress evi *597 dence seized in two searches, one at his business premises at the time of his arrest without a search warrant, and the other at his home with a search warrant after his arrest; the denial of his motion for a mistrial based on impermissible comment by the prosecutor during his opening to the jury; and deprivation of eEective assistance of counsel at the time of sentencing. We affirm one conviction and set aside the other.
1. Motion to suppress.
a. Warrantless search. The defendant contends that the police lacked probable cause to arrest him without a warrant and to search without a warrant the area within his immediate control at the time of his arrest at his workplace. We disagree.
We summarize the pertinent facts on which the judge based his denial of the motion. On November 18, 1988, the Hudson police arrested one Jose Braga for distribution of cocaine and trafficking in cocaine. He agreed to cooperate with the police by setting up a buy with his supplier, whom he identified as the defendant. On November 19, 1988, in the presence of the authorities he made two telephone calls to a person whom he identified as the defendant. The police traced the number called by Braga to the defendant’s residence. At approximately 10:00 a.m. that day, Braga arranged to meet the individual whom he had called at 18 Church Street in Hudson at 1:00 p.m. This was the address for Santiago Concrete Floors, Inc., a business owned and operated by the defendant.
After searching Braga for drugs and money and finding none, the police gave Braga $2,600 in marked currency and drove him to 18 Church Street for his 1:00 p.m. rendezvous. About 1:00 p.m. the defendant arrived in a pickup truck. Another police officer had observed the same truck leaving the defendant’s residence just before 1:00 p.m. The defendant left the truck, spoke to Braga for a few minutes, and then the two men entered the rear door of the building at 18 Church Street. The police did not observe the defendant carry anything into the building. A few minutes later, Braga exited the building and gave a prearranged signal that he had com *598 pleted the buy. Without stopping to check whether Braga actually had cocaine on his person (a subsequent search revealed 55.63 grams of cocaine), the police immediately entered the building and placed the defendant under arrest. From a work bench next to where the defendant was standing when the police entered, the police seized two crumpled fifty-dollar bills which were subsequently identified as part of the $2,600 buy money. At the time of the defendant’s arrest, the police had neither an arrest warrant nor a search warrant in their possession.
The defendant’s argument that the police lacked probable cause to arrest is based on the premise that Jose Braga must be treated as a confidential informant and that the underlying circumstances known to the police failed to satisfy the credibility or reliability and basis of knowledge tests for confidential informants.
Commonwealth
v.
Upton,
The defendant also challenged the entry of the police into the building and their search of the area within his immediate control without an arrest warrant or search warrant on the ground the police lacked exigent circumstances. The judge found the 1:00 p.m. buy was arranged at 10:00 a.m. on the same day but made no factual findings regarding exigent circumstances. This omission is not fatal where the ultimate conclusion is clearly evident from the record and implicit in the denial of the motion. See
Commonwealth
v.
Lanoue,
b. Search with a warrant. The defendant, however, is on solid ground with his challenge to the search of his home, *600 made with a search warrant 1 immediately after his arrest. The affidavit in support of the application for a warrant did not show probable cause for the search.
The affidavit contained the information, summarized above, which led to the defendant’s arrest, plus statements of the affiant that the search of Braga following the arrest had produced four plastic bags containing white powder. Those bags, the affidavit recited, field tested positive for cocaine, and the buy money, with the exception of the two fifty-dollar bills seized at the time of the defendant’s arrest, had not been recovered. The standard for probable cause is “whether [the magistrate] has a substantial basis for concluding that any of the articles described in the warrant are probably in the place to be searched .... Strong reason to suspect is not adequate.”
Commonwealth
v.
Upton,
2. Motion for a mistrial. During the prosecutor’s opening statement, the prosecutor told the jury that in the course of a narcotics investigation in Hudson, the police had arrested one Jose Braga for eleven counts of distribution and trafficking in cocaine. He then stated to the jury:
“Jose [Braga] . . . agreed to turn over his supplier to the Hudson Police Department. He agreed to make a purchase of drugs from someone named Orlando Olivares.”
The defendant made no objection to the prosecution’s opening remarks. At the conclusion of the defendant’s opening statement, the court, sua sponte, called a side bar conference to discuss those comments. The defendant then moved for a mistrial. The judge ruled he would not declare a mistrial but would give a limiting instruction, which he did. In his instructions to the jury, he told them to disregard the prosecutor’s statements, which he said were hearsay and could not be considered during the course of their deliberations. The judge also reminded the jurors of his previous instruction that opening statements were not evidence. During the course of the trial, the remark was not repeated.
The decision whether to declare a mistrial is a matter within the judge’s discretion.
Commonwealth
v.
Simmonds,
3.
Ineffective assistance of counsel.
The defendant claims that he was deprived of effective assistance of counsel because his counsel failed to address the court on his behalf at the time of sentencing and to present any information in mitigation of his punishment. See
Commonwealth
v.
Lykus,
The conviction of trafficking in cocaine based on the seizure of cocaine at the time of the defendant’s warrantless arrest is affirmed. The conviction of trafficking in cocaine based on the seizure of cocaine at the defendant’s residence is reversed and the verdict is set aside.
So ordered.
Notes
In a closet in the master bedroom of the home, the police found 30.79 grams of cocaine.
The trial judge so concluded.
The defendant received a lighter sentence than mandated by G. L. c. 94C, § 32E(b)(2), which on the date of the defendant’s offenses, November 19, 1988, provided for a minimum term of imprisonment of five years and a maximum of twenty years.
